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 A121663 #13 Jul 24 2025 19:25:54
%S A121663 1,2,3,6,4,8,12,24,5,10,15,30,20,40,60,120,6,12,18,36,24,48,72,144,30,
%T A121663 60,90,180,120,240,360,720,7,14,21,42,28,56,84,168,35,70,105,210,140,
%U A121663 280,420,840,42,84,126,252,168,336,504,1008,210,420,630,1260,840,1680
%N A121663 a(0) = 1; if n = 2^k, a(n) = k+2, otherwise a(n)=(A000523(n)+2)*a(A053645(n)).
%C A121663 Each n occurs A045778(n) times in the sequence.
%H A121663 Ivan Neretin, <a href="/A121663/b121663.txt">Table of n, a(n) for n = 0..8192</a>
%F A121663 G.f.: Product_{k>=0} (1 + (k + 2) * x^(2^k)). - _Ilya Gutkovskiy_, Aug 19 2019
%t A121663 f[0] := 1; f[n_] := If[(b = n - 2^(k = Floor[Log2[n]])) == 0, k + 2, (k + 2)*f[b]]; Table[f[n], {n, 0, 61}] (* _Ivan Neretin_, May 09 2015 *)
%o A121663 (Scheme) (define (A121663 n) (cond ((zero? n) 1) ((pow2? n) (+ 2 (A000523 n))) (else (* (+ 2 (A000523 n)) (A121663 (A053645 n))))))
%o A121663 (define (pow2? n) (and (> n 0) (zero? (A004198bi n (- n 1)))))
%Y A121663 Bisection of A096111.
%K A121663 nonn
%O A121663 0,2
%A A121663 _Antti Karttunen_, Aug 25 2006