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A257557 Expansion (x-1)/(x^5+2*x^3+2*x-1). 0
1, 1, 2, 6, 14, 33, 79, 188, 448, 1068, 2545, 6065, 14454, 34446, 82090, 195633, 466223, 1111080, 2647872, 6310280, 15038353, 35838673, 85408986, 203542550, 485072726, 1156001777, 2754927327, 6565409092, 15646364288, 37287655956, 88862131873 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..30.

FORMULA

a(n) = Sum_{k=0..n} Sum_{i=0..(n-k)/2} C(2*k,i)*C(n-2*i-1,n-2*i-k).

MATHEMATICA

CoefficientList[Series[(x - 1)/(x^5 + 2 x^3 + 2 x - 1), {x, 0, 33}], x] (* Vincenzo Librandi, Apr 30 2015 *)

PROG

(Maxima)

a(n):=sum(sum(binomial(2*k, i)*binomial(n-2*i-1, n-2*i-k), i, 0, (n-k)/2), k, 0, n);

CROSSREFS

Sequence in context: A232497 A089351 A005380 * A124612 A230439 A184697

Adjacent sequences:  A257554 A257555 A257556 * A257558 A257559 A257560

KEYWORD

nonn

AUTHOR

Vladimir Kruchinin, Apr 29 2015

EXTENSIONS

More terms from Vincenzo Librandi, Apr 30 2015

STATUS

approved

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Last modified July 17 16:58 EDT 2019. Contains 325107 sequences. (Running on oeis4.)