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 A204771 #30 May 21 2021 08:08:50 %S A204771 0,1,1,2,1,7,4,17,29,46,121,243,408,833,1929,3658,6353,12815,30844, %T A204771 61009,100133,216534,514233,930107,1686288,3352737,8264081,15163506, %U A204771 27077825,53153175,133991380,243114769,428343405,854649182,2120804377,3870970883,6937439304 %N A204771 a(n) = a(n-1) XOR (a(n-2)*3). %H A204771 Ivan Panchenko, <a href="/A204771/b204771.txt">Table of n, a(n) for n = 0..200</a> %F A204771 a(0)=0, a(1)=1, a(n) = a(n-1) XOR (a(n-2)*3), where XOR is the bitwise exclusive-OR operator. %o A204771 (Python) %o A204771 prpr = 0 %o A204771 prev = 1 %o A204771 for i in range(99): %o A204771 current = (prev)^(prpr*3) %o A204771 print(prpr, end=',') %o A204771 prpr = prev %o A204771 prev = current %Y A204771 Cf. A101624: a(n) = a(n-1) XOR (a(n-2)*2). %Y A204771 Cf. A101625: a(n) = a(n-1) XOR (a(n-2)*4). %K A204771 nonn,base,easy %O A204771 0,4 %A A204771 _Alex Ratushnyak_, May 07 2012