Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #10 Aug 19 2019 20:03:49
%S 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 60,90,180,120,240,360,720,7,14,21,42,28,56,84,168,35,70,105,210,140,
%U 280,420,840,42,84,126,252,168,336,504,1008,210,420,630,1260,840,1680
%N a(0) = 1; if n = 2^k, a(n) = k+2, otherwise a(n)=(A000523(n)+2)*a(A053645(n)).
%C Each n occurs A045778(n) times in the sequence.
%H Ivan Neretin, <a href="/A121663/b121663.txt">Table of n, a(n) for n = 0..8192</a>
%F G.f.: Product_{k>=0} (1 + (k + 2) * x^(2^k)). - _Ilya Gutkovskiy_, Aug 19 2019
%t 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 (Scheme:) (define (A121663 n) (cond ((zero? n) 1) ((pow2? n) (+ 2 (A000523 n))) (else (* (+ 2 (A000523 n)) (A121663 (A053645 n))))))
%o (define (pow2? n) (and (> n 0) (zero? (A004198bi n (- n 1)))))
%Y Bisection of A096111.
%K nonn
%O 0,2
%A _Antti Karttunen_, Aug 25 2006