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 A304756 #5 May 21 2018 11:28:36 %S A304756 1,2,4,6,19,3,32,12,9,18,62,5,488,31,23,87,1449,8,5505,20,36,61,14658, %T A304756 11,96,487,15,33,50871,22,190668,198,66,1448,44,7,736226,5504,492,25, %U A304756 3482516,35 %N A304756 Inverse of A304755: if A304755(k) = n, a(n) = k, or 0 if n does not occur in A304755. %C A304756 This is a left inverse of A304755, and also the right inverse if A304755 is a permutation of natural numbers, in which case the fallback clause is unnecessary. %F A304756 For n >= 1, a(A304755(n)) = n. %o A304756 (PARI) \\ Use the program given in A304755. %Y A304756 Cf. A304755 (inverse). %K A304756 nonn %O A304756 1,2 %A A304756 _Antti Karttunen_, May 20 2018