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 A083925 #6 Jan 30 2024 04:37:25 %S A083925 0,0,0,1,0,0,0,2,3,0,0,0,0,0,0,0,0,4,5,0,6,7,8,0,0,0,0,0,0,0,0,0,0,0, %T A083925 0,0,0,0,0,0,0,0,0,0,0,9,10,0,11,12,13,0,0,0,14,15,0,16,17,18,0,19,20, %U A083925 21,22,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 %N A083925 Inverse function of N -> N injection A057548. %C A083925 a(1)=0 because A057548(0)=1, but a(n) = 0 also for those n which do not occur as values of A057548. All positive natural numbers occur here once. %F A083925 a(n) = A083923(n)*A072771(n). %Y A083925 a(A057548(n)) = n for all n. Cf. A083926-A083929, A083935. %K A083925 nonn %O A083925 0,8 %A A083925 _Antti Karttunen_, May 13 2003