A162631 G.f. is the polynomial (1-x^3) * (1-x^6) * (1-x^9) * (1-x^12) * (1-x^15) * (1-x^18) * (1-x^21) * (1-x^24) * (1-x^27) * (1-x^30) * (1-x^33) * (1-x^36) * (1-x^39) / (1-x)^13.

1, 13, 91, 454, 1807, 6097, 18108, 48555, 119691, 274911, 594438, 1219920, 2391662, 4503266, 8179652, 14385775, 24574822, 40886248, 66405664, 105500290, 164245393, 250958800, 376862161, 556889086, 810661540, 1163656897

Offset: 0

Author

N. J. A. Sloane, Dec 02 2009

Keywords

• nonn

Comments

This is a row of the triangle in A162499. Only finitely many terms are nonzero.

Links

• G. C. Greubel, Table of n, a(n) for n = 0..260

Programs

Magma

m:=50; R:=PowerSeriesRing(Integers(), m); Coefficients(R!((1-x^3)*(1-x^6)*(1-x^9)*(1-x^12)*(1-x^15)*(1-x^18)*(1-x^21)*(1-x^24)*(1-x^27)*(1-x^30)*(1-x^33)*(1-x^36)*(1-x^39)/(1-x)^13)); // G. C. Greubel, Jul 06 2018

Mathematica

CoefficientList[Series[(Times@@(1-x^(3*Range[13])))/(1-x)^13,{x,0,30}],x] (* Harvey P. Dale, May 09 2016 *)

PARI

x='x+O('x^50); Vec((1-x^3)*(1-x^6)*(1-x^9)*(1-x^12)*(1-x^15)*(1-x^18)*(1-x^21)*(1-x^24)*(1-x^27)*(1-x^30)*(1-x^33)*(1-x^36)*(1-x^39)/(1-x)^13) \\ G. C. Greubel, Jul 06 2018