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A094938
a(n)=(-36^n/18)*B(2n,1/6)/B(2n,1/3) where B(n,x) is the n-th Bernoulli polynomial.
0
1, 63, 2511, 92583, 3352671, 120873303, 4353033231, 156723545223, 5642176768191, 203119525916343, 7312313393341551, 263243376303474663, 9476762394213697311, 341163453817290588183, 12281884406052838539471
OFFSET
1,2
FORMULA
a(n)=9^n/18*(4^n-2)
a(n)=9^(n-1)/2*(2^(2n)-2) - Harvey P. Dale, Mar 09 2018
G.f.: x*(1+18*x) / ( (36*x-1)*(9*x-1) ). - R. J. Mathar, Nov 15 2019
MATHEMATICA
LinearRecurrence[{45, -324}, {1, 63}, 20] (* Harvey P. Dale, Mar 09 2018 *)
PROG
(PARI) B(n, x)=sum(i=0, n, binomial(n, i)*bernfrac(i)*x^(n-i)); a(n)=(-36^n/18)*B(n, 1/6)/B(n, 1/3)
CROSSREFS
Cf. A096054.
Sequence in context: A143401 A075516 A004376 * A006110 A132051 A167987
KEYWORD
nonn,easy
AUTHOR
Benoit Cloitre, Jun 19 2004
EXTENSIONS
Incorrect recurrence formula deleted by Harvey P. Dale, Mar 09 2018
STATUS
approved