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 A239527 #13 Mar 21 2014 14:27:15 %S A239527 85,145,221,265,365,481,545,685,1405,1513,1985,2245,2813,2965,3281, %T A239527 3785,3961,4141,4705,5305,5513,5941,6161,6385,6613,7081,7813,8065, %U A239527 8321,9113,9385,10805,11101,11401,11705,12013,12961,13285,13945,16021,17113,17861,19405 %N A239527 Numbers k^2 + (k+1)^2 that can be expressed as a sum of two squares in exactly one other way. %C A239527 Subsequence of A166080. %H A239527 Giovanni Resta, <a href="/A239527/b239527.txt">Table of n, a(n) for n = 1..10000</a> %F A239527 Each number is of the form 2y^2 + 2y + 1. %e A239527 365 is in the sequence because 365 = 2^2+19^2 = 13^2+14^2; in the second representation 14-13=1. %t A239527 ok[n_] := 2 == Count[ PowersRepresentations[n, 2, 2], _?(! MemberQ[#, 0] &)]; Select[(2*#^2 + 2*# + 1) & /@ Range[100], ok] (* _Giovanni Resta_, Mar 21 2014 *) %Y A239527 Cf. A166080, A000404, A001844. %K A239527 nonn %O A239527 1,1 %A A239527 _Carmine Suriano_, Mar 21 2014