A021994 G.f.: 1/((1-x)(1-4x)(1-10x)(1-12x)).

1, 27, 495, 7735, 111111, 1517607, 20059495, 259217895, 3295741671, 41400518887, 515323813095, 6369067214055, 78280643507431, 957886180955367, 11679819118040295, 142009680313898215, 1722634678467548391

Offset

0,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..200

Index entries for linear recurrences with constant coefficients, signature (27,-234,688,-480).

Formula

a(n) = (27*12^(n+3) - 44*10^(n+3) + 33*4^(n+3) - 16)/4752. [Yahia Kahloune, Jun 27 2013]

a(0)=1, a(1)=27, a(2)=495, a(3)=7735; for n>3, a(n) = 27*a(n-1) -234*a(n-2) +688*a(n-3) -480*a(n-4). - Vincenzo Librandi, Jul 12 2013

Mathematica

CoefficientList[Series[1 / ((1 - x) (1 - 4 x) (1 - 10 x) (1 - 12 x)), {x, 0, 20}], x] (* Vincenzo Librandi, Jul 12 2013 *)

Prog

(Magma) I:=[1, 27, 495, 7735]; [n le 4 select I[n] else 27*Self(n-1)-234*Self(n-2)+688*Self(n-3)-480*Self(n-4): n in [1..25]]; /* or */ m:=25; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/((1-x)*(1-4*x)*(1-10*x)*(1-12*x)))); // Vincenzo Librandi, Jul 12 2013

Crossrefs

Sequence in context: A020969 A025956 A020724 * A020568 A021734 A019752

Adjacent sequences: A021991 A021992 A021993 * A021995 A021996 A021997

Keyword

nonn,easy

Author

N. J. A. Sloane.

Status

approved