A193104 G.f.: exp( Sum_{n>=1} 2*sigma(n*5^n)*x^n/n ).

1, 12, 165, 1820, 19610, 190006, 1823415, 16461130, 146258245, 1254022900, 10573576571, 86961051682, 705575418795, 5616255032890, 44167926438195, 342310177217866, 2624766747036662, 19886684916153110, 149283882397744910

Offset

0,2

Links

Table of n, a(n) for n=0..18.

Example

 G.f.: A(x) = 1 + 12*x + 165*x^2 + 1820*x^3 + 19610*x^4 + 190006*x^5 +...
log(A(x)) = 12*x + 186*x^2/2 + 1248*x^3/3 + 10934*x^4/4 + 39062*x^5/5 + 468744*x^6/6 +...+ 2*sigma(n*5^n)*x^n/n +...

Prog

 (PARI) {a(n)=polcoeff(exp(sum(m=1, n, 2*sigma(m*5^m)*x^m/m)+x*O(x^n)), n)}

Crossrefs

Sequence in context: A143583 A231541 A203372 * A046174 A055760 A056591

Adjacent sequences: A193101 A193102 A193103 * A193105 A193106 A193107

Keyword

nonn

Author

Paul D. Hanna, Jul 15 2011

Status

approved