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 A068125 #8 Dec 13 2017 05:56:29 %S A068125 0,1,3,5,6,8,10,11,15,16,20,21,25,26,28,30,31,35,36,40,41,45,46,50,51, %T A068125 53,55,56,60,61,65,66,70,71,75,76,78,80,81,85,86,90,91,95,96,100,101, %U A068125 105,106,110,111,115,116,120,121,125,126,128,130,131,135,136,140,141 %N A068125 Possible final digits of a triangular number. %e A068125 11 is a term as 1711 is a triangular number. %e A068125 13 is not a term as no triangular number is of the form 100k + 13. %Y A068125 Cf. A000217, A008954. %K A068125 base,easy,nonn %O A068125 1,3 %A A068125 _Amarnath Murthy_, Feb 21 2002 %E A068125 More terms from _Sascha Kurz_, Apr 03 2002 %E A068125 Offset and name edited by _Michel Marcus_, Dec 13 2017