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 A274631 #9 Jul 08 2016 13:06:15 %S A274631 1,2,4,3,5,6,7,8,10,9,11,12,13,14,16,15,17,18,19,20,22,21,24,23,26,25, %T A274631 28,27,30,29,32,31,34,33,36,35,38,37,39,40,42,41,44,43,46,45,48,47,50, %U A274631 49,52,51,54,53,56,55,58,57,59,60,62,61,64,63,66,65,68,67,70,69,72,71,74,73,76,75,78,77,79 %N A274631 First column of array in A274630. %Y A274631 Cf. A269526, A274630. %Y A274631 First differs from A131042 at a(23). - _Omar E. Pol_, Jul 08 2016 %K A274631 nonn %O A274631 1,2 %A A274631 _N. J. A. Sloane_, Jul 08 2016