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A124125 a(n)=(1/(4n))*sum(k=1,n,F(6k)*B(2n-2k)*binomial(2n,2k)) where F=Fibonacci numbers and B=Bernoulli numbers. 0
2, 19, 245, 3631, 58121, 973843, 16773677, 293759095, 5196109073, 92455824667, 1650850175669, 29537478199039, 529130102195225, 9485447592486691, 170110949757514301, 3051485664370912903, 54745886982174938657 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..17.

FORMULA

a(n)=(1/4)*(F(6n-3)+4^n*F(2n-1)+2*5^(n-1))

Empirical G.f.: -x*(68*x^4-597*x^3+346*x^2-51*x+2) / ((5*x-1)*(x^2-18*x+1)*(16*x^2-12*x+1)). [Colin Barker, Dec 01 2012]

PROG

(PARI) a(n)=(1/4)*(fibonacci(6*n-3)+4^n*fibonacci(2*n-1)+2*5^(n-1))

CROSSREFS

Cf. A111262.

Sequence in context: A106945 A211886 A125632 * A234505 A239108 A191806

Adjacent sequences:  A124122 A124123 A124124 * A124126 A124127 A124128

KEYWORD

nonn

AUTHOR

Benoit Cloitre, Nov 29 2006

STATUS

approved

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Last modified August 10 14:50 EDT 2020. Contains 336381 sequences. (Running on oeis4.)