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 A085200 #5 May 18 2024 14:45:57 %S A085200 0,1,0,2,0,3,0,0,0,4,0,6,0,0,0,5,0,7,0,0,0,0,0,8,0,0,0,0,0,0,0,0,0,9, %T A085200 0,14,0,0,0,11,0,16,0,0,0,0,0,19,0,0,0,0,0,0,0,0,0,10,0,15,0,0,0,12,0, %U A085200 17,0,0,0,0,0,20,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,13,0,18,0,0,0,0,0,21,0,0,0 %N A085200 Inverse function of N -> N injection A071155. %C A085200 a(0)=0 because A071155(0)=0, but a(n) = 0 also for those n which do not occur as values of A071155. All positive natural numbers occur here once. %Y A085200 a(A071155(n)) = n for all n. Cf. A080300. %K A085200 nonn %O A085200 0,4 %A A085200 _Antti Karttunen_, Jun 23 2003