A108012 a(n)= 8*a(n-1) -16*a(n-2) +4*a(n-4).

0, 4, 18, 76, 320, 1360, 5832, 25200, 109568, 478784, 2100512, 9244352, 40784896, 180284672, 798121088, 3537391360, 15692333056, 69661541376, 309407486464, 1374824795136, 6110847909888, 27168232722432, 120809925167104

Offset

0,2

Links

Table of n, a(n) for n=0..22.

Index entries for linear recurrences with constant coefficients, signature (8,-16,0,4)

Formula

G.f.: 2*x*(-2+7*x+2*x^2)/( (2*x^2+4*x-1) * (2*x^2-4*x+1)). [Sep 28 2009]

a(n) = A111567(n-1) + A090017(n+1) - A090017(n) - A090017(n-1), n>0.

Mathematica

M = {{0, 0, 0, 2}, {1, 4, 0, 0}, {0, 2, 0, 0}, {0, 0, 1, 4}} v[1] = {0, 1, 1, 2}; v[n_] := v[n] = M.v[n - 1]; digits = 50; a = Table[v[n][[1]], {n, 1, digits}]
LinearRecurrence[{8, -16, 0, 4}, {0, 4, 18, 76}, 30] (* Harvey P. Dale, Aug 11 2017 *)

Crossrefs

Sequence in context: A172159 A084213 A048664 * A291417 A017958 A017959

Adjacent sequences: A108009 A108010 A108011 * A108013 A108014 A108015

Keyword

nonn,easy

Author

Roger L. Bagula, May 30 2005

Extensions

Definition replaced by recurrence by the Associate Editors of the OEIS, Sep 28 2009

Status

approved