A227237 G.f.: Sum_{n>=0} x^n / (1-x)^sigma(n).

1, 1, 2, 5, 12, 29, 71, 175, 438, 1125, 2961, 7887, 20949, 54892, 141198, 357068, 895592, 2267345, 5937586, 16445988, 48475348, 149753749, 472130021, 1482046059, 4556113875, 13598311459, 39278316217, 109829580639, 298021031162, 787853185200, 2039529355219, 5201580347276

Offset

0,3

Comments

Here sigma(n) equals the sum of divisors of n (A000203).

Links

Paul D. Hanna, Table of n, a(n) for n = 0..720

Example

G.f.: A(x) = 1 + x + 2*x^2 + 5*x^3 + 12*x^4 + 29*x^5 + 71*x^6 + 175*x^7 +...
where
A(x) = 1 + x/(1-x) + x^2/(1-x)^3 + x^3/(1-x)^4 + x^4/(1-x)^7 + x^5/(1-x)^6 + x^6/(1-x)^12 + x^7/(1-x)^8 + x^8/(1-x)^15 + x^9/(1-x)^13 + x^10/(1-x)^18 +...

Prog

(PARI) {a(n)=polcoeff(1+sum(m=1, n, x^m/(1-x+x*O(x^n))^sigma(m)), n)}
for(n=0, 40, print1(a(n), ", "))

Crossrefs

Cf. A227236, A000203.

Sequence in context: A054198 A054196 A131710 * A005593 A122745 A166292

Adjacent sequences: A227234 A227235 A227236 * A227238 A227239 A227240

Keyword

nonn

Author

Paul D. Hanna, Jul 03 2013

Status

approved