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A306158
Inverse Weigh transform of 4^n.
5
4, 10, 20, 70, 204, 690, 2340, 8230, 29120, 104958, 381300, 1398430, 5162220, 19175130, 71582716, 268439590, 1010580540, 3817763040, 14467258260, 54975633906, 209430785460, 799645010850, 3059510616420, 11728124726270, 45035996273664, 173215372864590
OFFSET
1,1
LINKS
N. J. A. Sloane, Transforms
FORMULA
Product_{k>=1} (1+x^k)^a(k) = 1/(1-4x).
a(n) = 1/n*(4^n + Sum_{d<n and d|n} (-1)^(n/d)*d*a(d)).
EXAMPLE
(1+x)^4*(1+x^2)^10*(1+x^3)^20*(1+x^4)^70* ... = 1 + 4*x + 16*x^2 + 64*x^3 + 256*x^4 + ... .
CROSSREFS
Inverse Weigh transform of b^n: A306156 (b=2), A306157 (b=3), this sequence (b=4), A306159 (b=5).
Sequence in context: A047199 A038065 A249975 * A339784 A277970 A229884
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jun 23 2018
STATUS
approved