Stack Exchange

Mark Fischler

Warrenville, IL

I used to be a theoretical physicist, doing very early supergravity work as the first grad student of Peter vanNieuwenhuizen. I had a long career at the Fermi National Accelerator Laboratory, but have moved on to doing defense-related aeronautics work.

But mathematics has always been my strongest suit.

My Erdos number is 4.

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Top Questions

Prove that $\sum_{n=1}^\infty \frac{n!}{n^n}$is irrational.

sequences-and-series rationality-testing asked Mar 11, 2015 at 20:42

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Near-Pythagorean triplets: What are the general solutions to $a^2+b^2=c^2-1$?

diophantine-equations pythagorean-triples asked Aug 10, 2021 at 15:53

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If $a+b+c = 3abc$ and $\frac17 \leq k \leq 7$ prove $ \frac1{ka+b}+\frac1{kb+c}+\frac1{kc+a} \leq \frac3{k+1} $

inequality contest-math asked Mar 22, 2017 at 21:25

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Number of distinct angles that can be formed on a square grid

sequences-and-series combinatorics number-theory asked Nov 21, 2014 at 0:52

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Is there a clean non-contrived theorem that can only be proven by contradiction?

logic constructive-mathematics asked Jul 7, 2016 at 23:58

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Meromorphic, analytic, holomorphic and all that

complex-analysis asked May 26, 2016 at 15:03

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Limits of functions that can't be attacked by Taylor series or L'hopital's rule

calculus limits limits-without-lhopital asked Sep 12, 2016 at 21:31

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Why does $\sum_1^\infty \frac1{n^3}=\frac52\sum_1^\infty\frac{(-1)^{n-1}}{n^3\binom{2n}{n}}$?

riemann-zeta telescopic-series asked Jun 21, 2017 at 21:07

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Is it well known that for the Pythagorean spiral, $\sum_1^\infty\frac1{a_n+1} = \frac12$?

sequences-and-series pythagorean-triples asked Aug 29, 2017 at 21:18

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How ancient is the origin of the liturgical phrase "Baruch atah ... melech ha-olam"?

history blessing asked Apr 15, 2021 at 18:45

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Top Answers

Formula for the simple sequence 1, 2, 2, 3, 3, 4, 4, 5, 5, ...

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Turn off all lights in a ring-shaped palace

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Find some digits of $17!$

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If a coin toss is observed to come up as heads many times, does that affect the probability of the next toss?

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Why are irrational numbers such a big deal?

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Are there continuous functions for which the epsilon-delta property doesn't hold?

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Is there such a thing as a matrix of functions?

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% of % - Please Help Me Prove My Friend Wrong

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Is it mathematically wrong to prove the Intermediate Value Theorem informally?

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$S=\sqrt{1}+\sqrt{2}+\sqrt{3}+\sqrt{4}+\dots+\sqrt{m}$ is almost an integer. Find $m$

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Partial sums of primes

mathoverflow.net

Is there any continuous function that satisfies the following conditions?

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Mean vs. Median: When to Use?

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How can I rewrite recursive function as single formula?

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If $f(z)=\cfrac{z+1}{z-1}$ , then find $f^{1991}(2+i)$

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How to find a minimal polynomial

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Compute ${11 \choose 1} + {11 \choose 3} + ... + {11 \choose 11}$?

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Puzzle - Propose an algorithm to turn off lights

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Are two random vectors independent, iff every pair of components from each vector are independent?

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Need clarification on this l'Hopital's rule solution

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Why are fundamental theorems called fundamental?

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Need some guidance for my mathematics life

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Easy Double Sums Question: $\sum_{m=1}^{\infty} \sum_{n=1}^{\infty} \frac{1}{(m+n)!}$

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Doubt over the proof of Cayley- Hamilton heorem

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Limit involving infinity

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Compact notation for the product $k(k+1)(k+2)\cdots(k+n)$?

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Exponential Function Problem

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How to define $x^a$ for arbitrary real numbers $x$ and $a$

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What is the difference between advanced calculus, vector calculus, multivariable calculus, multivariable real analysis and vector analysis?

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Why does Givens rotation avoid iteration and Jacobi rotation doesn't in case of reducing a symmetric matrix to tridiagonal?

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