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A151787 a(1)=1; for n > 1, a(n)=3*2^{wt(n-1)-1}. 8
1, 3, 3, 6, 3, 6, 6, 12, 3, 6, 6, 12, 6, 12, 12, 24, 3, 6, 6, 12, 6, 12, 12, 24, 6, 12, 12, 24, 12, 24, 24, 48, 3, 6, 6, 12, 6, 12, 12, 24, 6, 12, 12, 24, 12, 24, 24, 48, 6, 12, 12, 24, 12, 24, 24, 48, 12, 24, 24, 48, 24, 48, 48, 96, 3, 6, 6, 12, 6, 12, 12, 24, 6, 12, 12, 24, 12, 24, 24, 48 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

wt(n) is the Hamming weight = binary weight of n (A000120).

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

FORMULA

From Robert Israel, Feb 27 2018: (Start)

For n > 1, a(2*n)=2*a(n).

a(2*n+1)=a(n+1).

G.f. g(x) satisfies g(x) = (2+1/x)*g(x^2) + x^2. (End)

MAPLE

wt:= n -> convert(convert(n, base, 2), `+`):

[1, seq(3*2^(wt(n-1)-1), n=2..100)]; # Robert Israel, Feb 27 2018

MATHEMATICA

a[n_] := If[n == 1, 1, 3*2^(Total[IntegerDigits[n-1, 2]]-1)];

Array[a, 100] (* Jean-Fran├žois Alcover, Mar 27 2019 *)

PROG

(PARI) a(n) = if (n==1, 1, 3*2^(hammingweight(n-1)-1)); \\ Michel Marcus, Feb 27 2018

CROSSREFS

Cf. A147582, A151779, A000120.

Sequence in context: A040007 A110634 A324467 * A113397 A226602 A307000

Adjacent sequences:  A151784 A151785 A151786 * A151788 A151789 A151790

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Jun 25 2009

EXTENSIONS

Definition corrected by Omar E. Pol, Mar 03 2015

STATUS

approved

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Last modified November 18 07:22 EST 2019. Contains 329252 sequences. (Running on oeis4.)