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 A092339 #17 Mar 11 2015 15:19:59 %S A092339 0,0,0,1,1,0,1,2,2,1,0,1,2,1,2,3,3,2,1,2,1,0,1,2,3,2,1,2,3,2,3,4,4,3, %T A092339 2,3,2,1,2,3,2,1,0,1,2,1,2,3,4,3,2,3,2,1,2,3,4,3,2,3,4,3,4,5,5,4,3,4, %U A092339 3,2,3,4,3,2,1,2,3,2,3,4,3,2,1,2,1,0,1,2,3,2,1,2,3,2,3,4,5,4,3,4,3,2 %N A092339 Number of adjacent identical digits in the binary representation of n. %C A092339 In binary: number of 00 blocks plus number of 11 blocks. (Note: the blocks can overlap. See the example below.) %D A092339 J.-P. Allouche and J. Shallit, Automatic Sequences, Cambridge Univ. Press, 2003, p. 84. %F A092339 Recurrence: a(2n) = a(n) + [n even], a(2n+1) = a(n) + [n odd]. %F A092339 a(n) = A014081(n) + A056973(n). %F A092339 For n>0, A227185(n) = a(n)+1. %F A092339 a(n) = A080791(A003188(n)) [because the sequence gives the number of nonleading zeros in binary Gray code expansion of n] - _Antti Karttunen_, Jul 05 2013 %e A092339 60 in binary is 111100, it has 4 blocks of adjacent digits, so a(60)=4. %e A092339 Equally, 60's binary Gray code expansion is A003188(60)=34, 100010 in binary, which contains four zeros. %o A092339 (PARI) a(n)=local(v); v=binary(n); sum(k=1, length(v)-1, v[k]==v[k+1]) %o A092339 (PARI) a(n)=if(n<1,0,if(n%2==0,a(n/2)+(n>0&&(n/2)%2==0),a((n-1)/2)+((n-1)/2)%2)) %o A092339 (Scheme) (define (A092339 n) (A080791 (A003188 n))) ;; _Antti Karttunen_, Jul 05 2013 %Y A092339 Cf. A005811. %K A092339 nonn,base %O A092339 0,8 %A A092339 _Ralf Stephan_, Mar 18 2004