A028032 Expansion of 1/((1-3x)(1-4x)(1-6x)(1-7x)).

1, 20, 255, 2650, 24521, 210840, 1725235, 13631750, 104995341, 793395460, 5908353815, 43502236050, 317443722961, 2299938136880, 16567618807995, 118785894675550, 848393691575381, 6040178746163100, 42890062369599775, 303884399490790250, 2149118961443240601

Offset

0,2

Links

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

Index entries for linear recurrences with constant coefficients, signature (20,-145,450,-504).

Formula

a(n) = (7^(n+3)-2*6^(n+3)+2*4^(n+3)-3^(n+3))/12. - Yahia Kahloune, May 30 2013

E.g.f.: exp(3*x)*(343*exp(4*x) - 432*exp(3*x) + 128*exp(x) - 27)/12. - Stefano Spezia, Sep 29 2022

Mathematica

CoefficientList[Series[1/((1-3x)(1-4x)(1-6x)(1-7x)), {x, 0, 20}], x] (* Harvey P. Dale, Jan 09 2019 *)

Crossrefs

Cf. A025986, A028027.

Sequence in context: A241228 A306290 A075469 * A348055 A025986 A028027

Adjacent sequences: A028029 A028030 A028031 * A028033 A028034 A028035

Keyword

nonn,easy

Author

N. J. A. Sloane

Status

approved