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A082987 a(n)=sum(k=0,n,3^k*F(k)) where F(k) is the k-th Fibonacci number. 0
0, 3, 12, 66, 309, 1524, 7356, 35787, 173568, 842790, 4090485, 19856568, 96384072, 467861331, 2271040644, 11023873914, 53510987541, 259747827852, 1260842371428, 6120257564955, 29708354037720, 144207380197758 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..22.

Index entries for linear recurrences with constant coefficients, signature (4,6,-9).

FORMULA

a(0)=0, a(1)=3, a(2)=12, a(n)=4a(n-1)+6a(n-2)-9a(n-3).

G.f.: 3*x^2 / ((x-1)*(9*x^2+3*x-1)). - Colin Barker, Jun 26 2013

MATHEMATICA

LinearRecurrence[{4, 6, -9}, {0, 3, 12}, 30] (* Harvey P. Dale, Feb 03 2019 *)

PROG

(PARI) a(n)=if(n<0, 0, sum(k=0, n-1, fibonacci(k)*3^k))

CROSSREFS

Cf. A014334.

Sequence in context: A144297 A007017 A183273 * A086836 A074513 A290147

Adjacent sequences:  A082984 A082985 A082986 * A082988 A082989 A082990

KEYWORD

nonn,easy

AUTHOR

Benoit Cloitre, May 29 2003

STATUS

approved

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Last modified September 27 12:51 EDT 2021. Contains 347688 sequences. (Running on oeis4.)