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 A203622 #13 May 21 2021 08:08:10 %S A203622 0,1,3,0,7,2,1,4,13,4,7,12,3,2,13,0,29,12,15,28,11,10,29,8,5,20,15,4, %T A203622 19,10,5,16,53,20,23,52,19,18,53,16,29,52,23,28,51,18,29,48,13,12,63, %U A203622 12,11,58,13,8,53,4,15,52,3,10,53,0,117,52,55,116,51,50,117 %N A203622 a(n) = (a(n-1) OR a(n-2)) XOR n. %C A203622 Indices of zeros: 2^(2x)-1, e.g. 0, 3, 15, 63, 255. %F A203622 a(0)=0, a(1)=1, a(n) = (a(n-1) OR a(n-2)) XOR n, where OR is the bitwise inclusive-or operator, XOR is the bitwise exclusive-or operator. %o A203622 (Python) %o A203622 prpr = 0 %o A203622 prev = 1 %o A203622 for n in range(2,77): %o A203622 current = (prev | prpr) ^ n %o A203622 print(prpr, end=',') %o A203622 prpr = prev %o A203622 prev = current %Y A203622 Cf. A182560. %K A203622 nonn,base,easy %O A203622 0,3 %A A203622 _Alex Ratushnyak_, May 06 2012