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 A050013 #6 Aug 06 2021 07:17:55 %S A050013 1,7,3,21,6,13,2,39,20,5,126,12,179,8,194,38,171,19,110,205,4,125,220, %T A050013 11,102,178,273,22,117,193,269,37,94,170,208,18,33,109,166,204,261,14, %U A050013 67,124,162,219,257,295,10,101,139,177,215,272,291,40,78,116,154 %N A050013 a(n) = position of n in A050012. %Y A050013 Cf. A050012. %K A050013 nonn,easy %O A050013 1,2 %A A050013 _Clark Kimberling_