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 A079257 #7 Mar 30 2012 17:27:18 %S A079257 0,1,4,5,6,10,15,16,17,18,21,22,23,24,25,28,36,45,55,56,57,66,78,91, %T A079257 105,120,121,122,136,137,138,139,140,141,142,143,153,154,155,156,157, %U A079257 158,159,160,161,171,172,173,174,175,176,177,178,179,180,190,210,231 %N A079257 a(n) is taken to be the smallest positive integer greater than a(n-1) which is consistent with the condition "n is a member of the sequence if and only if a(n) is a triangular number". %H A079257 B. Cloitre, N. J. A. Sloane and M. J. Vandermast, <a href="http://www.cs.uwaterloo.ca/journals/JIS/index.html">Numerical analogues of Aronson's sequence</a>, J. Integer Seqs., Vol. 6 (2003), #03.2.2. %H A079257 B. Cloitre, N. J. A. Sloane and M. J. Vandermast, <a href="http://arXiv.org/abs/math.NT/0305308">Numerical analogues of Aronson's sequence</a> (math.NT/0305308) %Y A079257 See A079000, A079253, A079254, A079256, A079258 for similar sequences. %K A079257 nonn,easy %O A079257 0,3 %A A079257 _N. J. A. Sloane_ and _Matthew Vandermast_, Feb 04 2003