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A193102 G.f.: exp( Sum_{n>=1} 2*sigma(n*3^n)*x^n/n ). 1
1, 8, 71, 478, 3248, 19674, 116885, 655064, 3602627, 19082622, 99353815, 503974610, 2518347829, 12341129010, 59691674707, 284343349874, 1339171125620, 6229010760982, 28686750790598, 130740792179088, 590661906472634, 2644740541614160 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..21.

EXAMPLE

G.f.: A(x) = 1 + 8*x + 71*x^2 + 478*x^3 + 3248*x^4 + 19674*x^5 +...

log(A(x)) = 8*x + 78*x^2/2 + 242*x^3/3 + 1694*x^4/4 + 4368*x^5/5 + 19680*x^6/6 + 52480*x^7/7 +...+ 2*sigma(n*3^n)*x^n/n +...

PROG

(PARI) {a(n)=polcoeff(exp(sum(m=1, n, 2*sigma(m*3^m)*x^m/m)+x*O(x^n)), n)}

CROSSREFS

Cf. A176310, A193103, A193104.

Sequence in context: A003364 A291892 A217328 * A038145 A198856 A320092

Adjacent sequences:  A193099 A193100 A193101 * A193103 A193104 A193105

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Jul 15 2011

STATUS

approved

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Last modified June 25 17:47 EDT 2019. Contains 324353 sequences. (Running on oeis4.)