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A157020
a(n) = Sum_{d|n} d*binomial(n/d+d-2,d-1).
11
1, 3, 4, 9, 6, 22, 8, 33, 28, 46, 12, 131, 14, 78, 136, 177, 18, 307, 20, 456, 302, 166, 24, 1149, 376, 222, 568, 1177, 30, 2387, 32, 1761, 958, 358, 2556, 5224, 38, 438, 1496, 7851, 42, 8317, 44, 4863, 9136, 622, 48, 20169, 6518, 11451, 3112, 8516, 54, 23734
OFFSET
1,2
COMMENTS
Equals row sums of triangle A157497. [Gary W. Adamson & Mats Granvik, Mar 01 2009]
LINKS
FORMULA
G.f.: Sum_{n>=1} n*x^n/(1-x^n)^n.
MAPLE
add( d*binomial(n/d+d-2, d-1), d=numtheory[divisors](n) ) ;
PROG
(PARI) N=66; x='x+O('x^N); Vec(sum(k=1, N, k*x^k/(1-x^k)^k)) \\ Seiichi Manyama, Sep 03 2019
CROSSREFS
Cf. A081543, A132065, A156833 (Mobius transform), A324158, A324159.
Sequence in context: A354112 A345270 A132065 * A180253 A264786 A055225
KEYWORD
easy,nonn,look
AUTHOR
R. J. Mathar, Feb 21 2009
STATUS
approved