A028075 Expansion of 1/((1-3x)(1-6x)(1-7x)(1-9x)).

1, 25, 400, 5230, 60991, 661675, 6836950, 68263360, 664838581, 6356961325, 59947423900, 559395635890, 5177995501771, 47632122760975, 436056971109250, 3977028159426820, 36166503547714561, 328145135909292625, 2972035570568581000, 26880644285129620150, 242859379929646660951

Offset

0,2

Links

Table of n, a(n) for n=0..20.

Index entries for linear recurrences with constant coefficients, signature (25,-225,855,-1134).

Formula

a(n) = (2*9^(n+3) - 9*7^(n+3) + 8*6^(n+3) - 3^(n+3))/72. [Yahia Kahloune, Jun 10 2013]

Mathematica

CoefficientList[Series[1/((1-3x)(1-6x)(1-7x)(1-9x)), {x, 0, 20}], x] (* or *) LinearRecurrence[{25, -225, 855, -1134}, {1, 25, 400, 5230}, 20] (* Harvey P. Dale, May 06 2018 *)

Prog

(Magma) [(2*9^(n+3)-9*7^(n+3)+8*6^(n+3)-3^(n+3))/72: n in [0..20]]; // Vincenzo Librandi, May 30 2019

Crossrefs

Sequence in context: A286719 A174515 A028116 * A042204 A028112 A238511

Adjacent sequences: A028072 A028073 A028074 * A028076 A028077 A028078

Keyword

nonn,easy

Author

N. J. A. Sloane

Status

approved