A193102 G.f.: exp( Sum_{n>=1} 2*sigma(n*3^n)*x^n/n ).

1, 8, 71, 478, 3248, 19674, 116885, 655064, 3602627, 19082622, 99353815, 503974610, 2518347829, 12341129010, 59691674707, 284343349874, 1339171125620, 6229010760982, 28686750790598, 130740792179088, 590661906472634, 2644740541614160

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: A376053 A291892 A217328 * A038145 A198856 A320092

Adjacent sequences: A193099 A193100 A193101 * A193103 A193104 A193105

Keyword

nonn

Author

Paul D. Hanna, Jul 15 2011

Status

approved