A162539 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)^6.

1, 6, 21, 55, 120, 231, 405, 660, 1014, 1484, 2085, 2829, 3724, 4773, 5973, 7315, 8784, 10359, 12013, 13713, 15420, 17091, 18681, 20145, 21440, 22527, 23373, 23952, 24246, 24246, 23952, 23373, 22527, 21440, 20145, 18681, 17091, 15420, 13713

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..57

Programs

Magma

m:=58; 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)^6)); /* complete row */ // G. C. Greubel, Jul 06 2018

Mathematica

CoefficientList[ Series[Times @@ (1 - x^(3 Range@6))/(1 - x)^6, {x, 0, 70}], x] (* G. C. Greubel, Jul 06 2018 and slightly modified by Robert G. Wilson v, Jul 23 2018 *)

PARI

x='x+O('x^58); Vec((1-x^3)*(1-x^6)*(1-x^9)*(1-x^12)*(1-x^15)*(1-x^18)/(1-x)^6) /* complete row */ \\ G. C. Greubel, Jul 06 2018