Volume 56
, Issue 2


Dear Readers,
welcome to this issue of Parabola! This theme of this issue is the “natural” numbers.

We look at number triples that almost - but not quite - satisfy Pythagoras' Theorem: the quasi-Pythagorean triads.

Nearly a century and a half since its introduction, Sylvester's sequence continues to be relevant as it is the focus of open conjectures.

This article provides a brief introduction to aliquot sums and presents a proof of a beautiful identity that these sums satisfy.

In this paper, we prove theorems that simplify the famous Sierpinski Number Problem. We also develop a method for prime numbers that would aid the current sequential searching techniques.

This note briefly gives advice on how to write a Parabola article - or any mathematical article.

An odd comic about even numbers.

Q1622 Find the sum of the digits of
$$S=1+11+111+1111+\cdots+\overbrace{11\cdots11}^{999\ \rm digits}\,,$$
where the last term on the right hand side has $999$ digits, all equal to $1$.