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A193201 G.f.: A(x) = Sum_{n>=0} x^n / Product_{d|n} (1 - x^d)^(n/d). 0
1, 1, 2, 4, 9, 18, 39, 81, 170, 355, 748, 1576, 3334, 7054, 14935, 31591, 66732, 140708, 296379, 624389, 1317807, 2790095, 5930254, 12652077, 27071714, 58019282, 124377335, 266404590, 569755992, 1216513200, 2593884456, 5526424017, 11773433242 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..32.

EXAMPLE

G.f.: A(x) = 1 + x + 2*x^2 + 3*x^3 + 6*x^4 + 9*x^5 + 20*x^6 + 31*x^7 + ...

where:

A(x) = 1 + x/(1-x) + x^2/((1-x)^2*(1-x^2)) + x^3/((1-x)^3*(1-x^3)) + x^4/((1-x)^4*(1-x^2)^2*(1-x^4)) + x^5/((1-x)^5*(1-x^5)) + x^6/((1-x)^6*(1-x^2)^3*(1-x^3)^2*(1-x^6)) + ...

PROG

(PARI) {a(n)=local(A=1); A=1+sum(m=1, n, x^m/prod(d=1, m, if(m%d==0, (1-x^d +x*O(x^n))^(m/d), 1))); polcoeff(A, n)}

CROSSREFS

Sequence in context: A036610 A219755 A289846 * A038044 A189911 A026732

Adjacent sequences:  A193198 A193199 A193200 * A193202 A193203 A193204

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Jul 17 2011

STATUS

approved

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Last modified October 18 16:40 EDT 2021. Contains 348068 sequences. (Running on oeis4.)