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 A072650 #7 May 18 2024 14:51:05 %S A072650 0,1,2,1,4,3,2,3,8,5,6,5,4,3,6,3,16,9,10,9,12,7,10,7,8,5,6,5,12,7,6,7, %T A072650 32,17,18,17,20,11,18,11,24,13,14,13,20,11,14,11,16,9,10,9,12,7,10,7, %U A072650 24,13,14,13,12,7,14,7,64,33,34,33,36,19,34,19,40,21,22,21,36,19,22,19 %N A072650 Starting from the right (the least significant end) rewrite 0 to 0 and x1 to 1 in the binary expansion of n. %F A072650 A048679(n) = a(A003714(n)). %e A072650 I.e. 23 is 10111 in binary, which after rewriting is 111, thus a(23) = 7, while 38 is 100110 in binary, which after the rewriting is 10010, i.e. a(38) = 18. %o A072650 (MIT/GNU Scheme) (define (A072650 n) (let loop ((n n) (s 0) (i 0)) (cond ((zero? n) s) ((even? n) (loop (floor->exact (/ n 2)) s (1+ i))) (else (loop (floor->exact (/ n 4)) (+ s (expt 2 i)) (1+ i)))))) %Y A072650 Cf. A003714, A048679. %K A072650 nonn %O A072650 0,3 %A A072650 _Antti Karttunen_, Jun 02 2002