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 A248599 #62 Jan 24 2015 15:17:25 %S A248599 11,13,22,23,26,33,37,39,44,46,47,52,55,59,61,65,66,69,71,73,74,77,78, %T A248599 83,88,91,92,94,97,99,104,107,109,110,111,115,117,118,122,130,131,132, %U A248599 138,141,142,146,148,154,156,157,161,165,166,167,176,177,179,181 %N A248599 Positive integers whose square is expressible in exactly one way as x^2 + 4xy + y^2, with 0 < x < y. %H A248599 Colin Barker, <a href="/A248599/b248599.txt">Table of n, a(n) for n = 1..750</a> %e A248599 11 is in the sequence because the only solution to x^2 + 4xy + y^2 = 121 with 0 < x < y is (x,y) = (4,5). %Y A248599 Cf. A232437, A084645, A254063, A254064. %K A248599 nonn %O A248599 1,1 %A A248599 _Colin Barker_, Jan 21 2015