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A113415 Expansion of Sum_{k>0} x^k/(1-x^(2k))^2. 2
1, 1, 3, 1, 4, 3, 5, 1, 8, 4, 7, 3, 8, 5, 14, 1, 10, 8, 11, 4, 18, 7, 13, 3, 17, 8, 22, 5, 16, 14, 17, 1, 26, 10, 26, 8, 20, 11, 30, 4, 22, 18, 23, 7, 42, 13, 25, 3, 30, 17, 38, 8, 28, 22, 38, 5, 42, 16, 31, 14, 32, 17, 55, 1, 44, 26, 35, 10, 50, 26, 37, 8, 38, 20, 65, 11, 50, 30, 41 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..79.

FORMULA

G.f.: Sum_{k>0} x^k/(1-x^(2k))^2 = Sum_{k>0} k x^(2k-1)/(1-x^(2k-1)).

PROG

(PARI) a(n)=if(n<1, 0, sumdiv(n, d, if(d%2, (d+1)/2)))

CROSSREFS

Sequence in context: A082909 A029151 A102595 * A054019 A230877 A209613

Adjacent sequences:  A113412 A113413 A113414 * A113416 A113417 A113418

KEYWORD

nonn

AUTHOR

Michael Somos, Oct 29 2005

STATUS

approved

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Last modified March 19 15:02 EDT 2019. Contains 321330 sequences. (Running on oeis4.)