A025961 Expansion of 1/((1-2x)(1-4x)(1-5x)(1-9x)).

1, 20, 263, 2902, 29289, 281472, 2630731, 24196634, 220500797, 1998686404, 18061169919, 162923877246, 1468215185425, 13223572329416, 119060866122227, 1071793518338338, 9647378871105573, 86832630229860108

Offset

0,2

Links

Table of n, a(n) for n=0..17.

Index entries for linear recurrences with constant coefficients, signature (20, -137, 382, -360).

Formula

a(0)=1, a(1)=20, a(2)=263, a(3)=2902, a(n)=20*a(n-1)-137*a(n-2)+ 382*a(n-3)- 360*a(n-4). [Harvey P. Dale, Dec 08 2011]

a(n) = -4*2^n/21 +32*4^n/5 -125*5^n/12 +729*9^n/140. - R. J. Mathar, Jun 20 2013

Mathematica

CoefficientList[Series[1/((1-2x)(1-4x)(1-5x)(1-9x)), {x, 0, 30}], x] (* or *) LinearRecurrence[{20, -137, 382, -360}, {1, 20, 263, 2902}, 30] (* Harvey P. Dale, Dec 08 2011 *)

Crossrefs

Sequence in context: A041764 A022111 A025943 * A208948 A278408 A229562

Adjacent sequences: A025958 A025959 A025960 * A025962 A025963 A025964

Keyword

nonn,easy

Author

N. J. A. Sloane.

Status

approved