0,2

a(n)={{19*[((3+sqrt(5))/2)^n - ((3-sqrt(5))/2)^n]-9*[((3+sqrt(5))/2)^(n-1) - ((3-sqrt(5))/2)^(n-1)]}/sqrt(5)} - 8.

G.f.(x)=(1+7x)/(1-x)(1-3x+x^2).

Fibonacci(2n+5) + 2*Lucas(2n) - 8.

Cf. A055850.

Sequence in context: A031427 A059142 A064798 this_sequence A064768 A135719 A089776

Adjacent sequences: A056121 A056122 A056123 this_sequence A056125 A056126 A056127

easy,nonn

Barry E. Williams, Jul 07 2000