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 A115837 #7 Sep 24 2018 16:53:14 %S A115837 1,3,4,6,9,10,12,13,14,15,18,19,21,24,27,30,31,32,33,36,37,39,40,41, %T A115837 42,43,44,45,46,47,48,51,54,57,58,59,60,63,64,66,69,72,75,78,81,84,87, %U A115837 90,93,94,95,96,97,98,99,100,101,102,105,108,111,112,113,114,117,118,120 %N A115837 Self-describing sequence. The n-th integer of the sequence indicates how many integers of the sequence are strictly < 3n. %C A115837 Terms computed by Gilles Sadowski. In building step by step the sequence one has sometimes the choice for an integer. If so take the smallest available one. %C A115837 Is this the same sequence as A080710? - _Andrew S. Plewe_, May 08 2007 %e A115837 a(7)=12 because there are 12 integers in the sequence which are strictly < 21 (they are 1,3,4,6,9,10,12,13,14,15,18,19). %K A115837 base,easy,nonn %O A115837 1,2 %A A115837 _Eric Angelini_, Feb 01 2006