A093123 Third binomial transform of Fibonacci(3n-1) (A015448).

1, 4, 20, 120, 800, 5600, 40000, 288000, 2080000, 15040000, 108800000, 787200000, 5696000000, 41216000000, 298240000000, 2158080000000, 15616000000000, 112998400000000, 817664000000000, 5916672000000000, 42813440000000000

Offset

0,2

Links

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

Index entries for linear recurrences with constant coefficients, signature (10, -20).

Formula

G.f.: (1-6x)/(1-10x+20x^2).

a(n) = (5-sqrt(5))*(5+sqrt(5))^n/10 + (5+sqrt(5))*(5-sqrt(5))^n/10.

a(n) = 2^n*A093129(n).

Crossrefs

Cf. A000045, A015448, A093129.

Sequence in context: A089498 A046729 A277920 * A092055 A187848 A370653

Adjacent sequences: A093120 A093121 A093122 * A093124 A093125 A093126

Keyword

easy,nonn

Author

Paul Barry, Mar 23 2004

Status

approved