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 A185980 #10 Dec 01 2016 01:39:43 %S A185980 16,31,42,46,51,56,72,76,81,94,106,111,121,123,126,133,141,146,156, %T A185980 157,172,174,181,186,191,196,198,211,216,225,226,237,241,246,256,259, %U A185980 268,281,286,289,291,297,301,306,310,315,321,326,328,331,336,342,346,354 %N A185980 Nontriangular numbers that are the sum of two (positive) triangular numbers in more than one way. %C A185980 A000217(0)=0, but it will not appear as a summand. %C A185980 A185979 uses only positive triangular summands, and includes triagonal (or body diagonal) numbers like 231, 276, 406, 666, ... %F A185980 See the one given for A185978, taking into account multiplicities. %e A185980 16 = 15 + 1 = 10 + 6. %e A185980 81 = 45 + 36 = 66 + 15 = 78 + 3. %Y A185980 Cf. A000217, A020756 (sums of two triangular numbers), A051533 (sums of two positive triangular numbers), A064816, A185978, A185979. %K A185980 nonn,easy %O A185980 1,1 %A A185980 _Wolfdieter Lang_, Feb 15 2011