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A190315 Central coefficients of the Riordan matrix ((1-x-x^2)/(1-2x-x^2),(x-x^2-x^3)/(1-2x-x^2)) (A190215). 2
1, 2, 9, 48, 265, 1500, 8638, 50360, 296325, 1756160, 10467556, 62683896, 376838098, 2272896626, 13747543035, 83354081728, 506467851061, 3083121435312, 18799746616104, 114804614071760, 702016963933404, 4297947201746176, 26342178216979384 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..1000 (terms 0..100 from Vincenzo Librandi)

FORMULA

a(n) = T(2*n,n), where T(n,k)=A190215(n,k).

a(n) = Sum_{i=0..n} binomial(n+i,n)*Sum_{j=0..n-i} binomial(i+j-1,j)*binomial(j,n-i-j).

MATHEMATICA

Table[Sum[Binomial[n+i, n]Sum[Binomial[i+j-1, j]Binomial[j, n-i-j], {j, 0, n-i}], {i, 0, n}], {n, 0, 22}]

PROG

(Maxima) makelist(sum(binomial(n+i, n)*sum(binomial(i+j-1, j)*binomial(j, n-i-j), j, 0, n-i), i, 0, n), n, 0, 22);

(PARI) for(n=0, 30, print1(sum(k=0, n, binomial(n+k, n)*sum(j=0, n-k, binomial(k+j-1, j)*binomial(j, n-k-j))), ", ")) \\ G. C. Greubel, Mar 04 2018

CROSSREFS

Cf. A190215.

Sequence in context: A306356 A188818 A047139 * A190253 A174687 A047059

Adjacent sequences:  A190312 A190313 A190314 * A190316 A190317 A190318

KEYWORD

nonn

AUTHOR

Emanuele Munarini, May 10 2011

STATUS

approved

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Last modified April 18 12:27 EDT 2019. Contains 322209 sequences. (Running on oeis4.)