0,3

The coefficients of the recursion for a(n) are given by the 6th row of A145152.

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (6,-15,20,-14,1,9,-10,5,-1).

a(n) = 6a(n-1) -15a(n-2) +20a(n-3) -14a(n-4) +a(n-5) +9a(n-6) -10a(n-7) +5a(n-8) -a(n-9).

col:= proc(k) local l, j, M, n; l:= `if` (k=0, [1, 0, 0, 1], [seq (coeff ( -(1-x-x^4) *(1-x)^(k-1), x, j), j=1..k+3)]); M:= Matrix (nops(l), (i, j)-> if i=j-1 then 1 elif j=1 then l[i] else 0 fi); `if` (k=0, n->(M^n)[2, 3], n->(M^n)[1, 2]) end: a:= col(6): seq(a(n), n=0..40);

CoefficientList[Series[x / ((1 - x - x^4) (1 - x)^5), {x, 0, 40}], x] (* Vincenzo Librandi, Jun 06 2013 *)

LinearRecurrence[{6, -15, 20, -14, 1, 9, -10, 5, -1}, {0, 1, 6, 21, 56, 127, 259, 490, 876}, 40] (* Harvey P. Dale, Aug 14 2013 *)

(PARI) concat(0, Vec(1/(1-x-x^4)/(1-x)^5+O(x^99))) \\ Charles R Greathouse IV, Sep 25 2012

6th column of A145153. Cf. A145152.

Sequence in context: A145455 A346893 A337895 * A392587 A256571 A247904

Adjacent sequences: A145131 A145132 A145133 * A145135 A145136 A145137

nonn,easy

Alois P. Heinz, Oct 03 2008

approved