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 A304090 #7 May 17 2018 17:03:32 %S A304090 1,2,4,6,8,3,14,26,66,9,34,5,96,15,11,6531,193,67,386,7,17,35,770,27, %T A304090 6146,97,7484,19,1538,10,3074,1210614,37,194,21,71,14647,387,99,29, %U A304090 30533,16,60824,39,69,771,122349,6532,367278,6147,196,101,245225,7485,41,31,389,1539,688293,12,1535694,3075,73 %N A304090 Inverse of A282291: if A282291(k) = n, a(n) = k, or 0 if n does not occur in A282291. %C A304090 This is a left inverse of A282291, and also the right inverse if A282291 is a permutation of natural numbers, in which case the fallback-clause is unnecessary. %F A304090 For n >= 1, a(A282291(n)) = n. %o A304090 (PARI) \\ Use the program given in A282291. %Y A304090 Cf. A282291, A302854. %K A304090 nonn %O A304090 1,2 %A A304090 _Antti Karttunen_, May 17 2018