This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A240775 #15 Apr 13 2014 14:11:05
%S A240775 1,121,169,289,361,529
%N A240775 The six values n in each interval [i*840, (i+1)*840), where i >= 0, for which Mordell's formulas do NOT provide a three-Egyptian-fraction solution for 4/n.
%C A240775 Erdős and Straus conjectured that for all integers n >= 2, the rational number 4/n can be expressed as an Egyptian fraction with exactly three unit fractions -- that is, 4/n = 1/x + 1/y + 1/z where x, y and z are positive integers. The conjecture has been verified to high values of n, and Mordell has provided formulas to compute x, y and z for many n. The values of n NOT included in Mordell's formulas are those for which n modulo 840 = {an element of this sequence}. Each element is the square of a prime.
%D A240775 Louis J. Mordell, Diophantine Equations, Academic Press, 1967, 287-290.
%K A240775 nonn,fini,full
%O A240775 1,2
%A A240775 _Kenneth Vollmar_, Apr 12 2014