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 A163901 #2 Mar 31 2012 13:21:18 %S A163901 0,1,16,20,21,256,260,261,320,321,336,340,341,4096,4100,4101,4160, %T A163901 4161,4176,4180,4181,5120,5121,5136,5140,5141,5376,5380,5381,5440, %U A163901 5441,5456,5460,5461,65536,65540,65541,65600,65601,65616,65620,65621 %N A163901 The positions i where A163355(i) = i, that is, the fixed points of permutation A163355. %C A163901 Alternatively, the positions of zeros in A163900. %Y A163901 a(n) = A000695(A165404(n)). Same sequence in base-4: A165406. See also A163902, A163903, A163910. %K A163901 nonn %O A163901 0,3 %A A163901 _Antti Karttunen_, Sep 19 2009