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 A215604 #9 Mar 26 2025 18:45:32 %S A215604 0,1,0,1,1,2,1,2,0,1,0,1,1,2,1,2,1,2,1,2,2,0,2,0,1,2,1,2,2,0,2,0,0,1, %T A215604 0,1,1,2,1,2,0,1,0,1,1,2,1,2,1,2,1,2,2,0,2,0,1,2,1,2,2,0,2,0,1,2,1,2, %U A215604 2,0,2,0,1,2,1,2,2,0,2,0,2,0,2,0,0,1,0,1,2 %N A215604 a(0)=0, a(n) = (n + a(floor(n/2))) mod 3. %o A215604 (Python) %o A215604 TOP = 1000 %o A215604 a = [0]*TOP %o A215604 for n in range(1, TOP): %o A215604 print(a[n-1], end=', ') %o A215604 a[n] = (n + a[n//2]) % 3 %Y A215604 Cf. A010060 ((n + a(floor(n/2))) mod 2). %Y A215604 Cf. A051065 ((n + a(floor(n/3))) mod 2). %Y A215604 Cf. A053838 ((n + a(floor(n/3))) mod 3). %K A215604 nonn,easy %O A215604 0,6 %A A215604 _Alex Ratushnyak_, Aug 17 2012