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A124430 Eigenvector of triangle A124428. 2
1, 1, 2, 3, 7, 13, 31, 61, 144, 296, 714, 1534, 3761, 8303, 20495, 46115, 114461, 261445, 651114, 1503207, 3749017, 8726147, 21788311, 51072555, 127698665, 301244477, 754496298, 1790598079, 4494019431, 10726676701, 26983034009 (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/2]} a(k)*C([n/2],k)*C([(n+1)/2],k) for n>0, with a(0)=1.

EXAMPLE

a(5) = 1*a(0) + 6*a(1) + 3*a(2) = 1*1 + 6*1 + 3*2 = 13;

a(6) = 1*a(0) + 9*a(1) + 9*a(2) + 1*a(3) = 1*1 + 9*1 + 9*2 + 1*3 = 31.

Triangle A124428(n,k) = C([n/2],k)*C([(n+1)/2],k) begins:

1;

1;

1, 1;

1, 2;

1, 4, 1;

1, 6, 3;

1, 9, 9, 1;

1, 12, 18, 4;

1, 16, 36, 16, 1; ...

PROG

(PARI) {a(n)=if(n==0, 1, sum(k=0, n\2, a(k)*binomial(n\2, k)*binomial((n+1)\2, k)))}

CROSSREFS

Cf. A124428, A124429.

Sequence in context: A242389 A102644 A014234 * A002013 A171416 A193530

Adjacent sequences:  A124427 A124428 A124429 * A124431 A124432 A124433

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Oct 31 2006

STATUS

approved

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Last modified January 20 16:46 EST 2019. Contains 319335 sequences. (Running on oeis4.)