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 A182509 #17 Jun 05 2025 11:11:07 %S A182509 0,1,3,1,8,14,16,37,61,89,144,244,392,633,1023,1641,2680,4306,6968, %T A182509 11261,18209,29489,47688,77200,124880,202073,326931,528993,855952, %U A182509 1384942,2240896,3625869,5866797,9492633,15359464,24852068,40211496,65063537,105275007 %N A182509 a(0)=0, a(1)=1, a(n)=(a(n-1) XOR n) + a(n-2). %C A182509 Terms with indices 6k+1, 6k+2, 6k+3 are odd, all other terms are even. %F A182509 a(0)=0, a(1)=1, a(n)=(a(n-1) XOR n) + a(n-2), where XOR is the bitwise exclusive-or operator. %o A182509 (Python) %o A182509 prpr = 0 %o A182509 prev = 1 %o A182509 for n in range(2,99): %o A182509 current = (prev ^ n) + prpr %o A182509 print(prpr, end=', ') %o A182509 prpr = prev %o A182509 prev = current %K A182509 nonn,base,easy %O A182509 0,3 %A A182509 _Alex Ratushnyak_, May 03 2012