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 A265140 #24 Dec 13 2015 07:32:08
%S A265140 4,7,9,11,13,18,21,22,24,25,27,29,34,36,37,38,39,42,43,48,49,55,56,57,
%T A265140 58,60,61,64,65,66,67,69,70,72,73,79,83,84,87,88,91,92,93,97,99,100,
%U A265140 101,102,108,112,114,115,119,120,127,130,135,136,137,139,142,144
%N A265140 Numbers that are the sum of two distinct nonzero triangular numbers in exactly one way.
%t A265140 r = 144; lst = Table[0, {r}]; lim = Floor[Sqrt[8*r - 7]]; Do[num = (i^2 + i)/2 + (j^2 + j)/2; If[num <= r, lst[[num]]++], {i, lim}, {j, i - 1}]; Flatten@Position[lst, 1]
%Y A265140 Cf. A000217, A051533, A260647, A262749 (more than one way), A265134 (exactly two ways), A265135 (more than two ways), A265136 (exactly three ways), A265137 (more than three ways), A265138 (exactly four ways).
%K A265140 nonn
%O A265140 1,1
%A A265140 _Arkadiusz Wesolowski_, Dec 02 2015