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 A275727 #19 Mar 12 2025 07:38:52 %S A275727 0,1,2,3,2,3,4,5,6,7,6,7,4,5,6,7,6,7,4,5,6,7,6,7,8,9,10,11,10,11,12, %T A275727 13,14,15,14,15,12,13,14,15,14,15,12,13,14,15,14,15,8,9,10,11,10,11, %U A275727 12,13,14,15,14,15,12,13,14,15,14,15,12,13,14,15,14,15,8,9,10,11,10,11,12,13,14,15,14,15,12,13,14,15 %N A275727 a(0) = 0, for n >= 1, a(n) = A275736(n) + 2*a(A257684(n)). %C A275727 a(n) has ones in those positions of its base-2 representation where n has nonzero digits in its factorial base representation. %H A275727 Antti Karttunen, <a href="/A275727/b275727.txt">Table of n, a(n) for n = 0..40320</a> %H A275727 <a href="/index/Bi#binary">Index entries for sequences related to binary expansion of n</a> %H A275727 <a href="/index/Fa#facbase">Index entries for sequences related to factorial base representation</a> %F A275727 a(0) = 0, for n >= 1, a(n) = A275736(n) + 2*a(A257684(n)). %F A275727 a(n) = A048675(A275733(n)). %F A275727 Other identities and observations. For all n >= 0: %F A275727 A000120(a(n)) = A060130(n). %e A275727 For n=19, A007623(19) = 301, thus a(19) = 5 because A007088(5) = 101. %o A275727 (Scheme, with memoization-macro definec) %o A275727 (definec (A275727 n) (if (zero? n) n (+ (A275736 n) (* 2 (A275727 (A257684 n)))))) %o A275727 (define (A275727 n) (A048675 (A275733 n))) %Y A275727 Cf. A000120, A007088, A007623, A048675, A060130, A257684, A275733, A275736. %Y A275727 Cf. also A275728. %K A275727 nonn,base,look %O A275727 0,3 %A A275727 _Antti Karttunen_, Aug 09 2016