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 A080090 #10 Apr 25 2020 03:18:25 %S A080090 0,1,2,4,10,58,43,191,246,320,2000,1602,4172,7598,21843,36520,27737 %N A080090 a(n) is the index of the first occurrence of n in A080071, or 0 for those n>0 which never occur in A080071. %C A080090 17 does not occur among the first 404631 terms of A080071. %Y A080090 Cf. A080071. %K A080090 nonn,more %O A080090 0,3 %A A080090 _Antti Karttunen_, Jan 27 2003