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A047073 Sum{T(i,n-i): i=0,1,...,n}, array T as in A047072. 3
1, 2, 4, 4, 8, 12, 24, 40, 80, 140, 280, 504, 1008, 1848, 3696, 6864, 13728, 25740, 51480, 97240, 194480, 369512, 739024, 1410864, 2821728, 5408312, 10816624, 20801200, 41602400, 80233200, 160466400, 310235040, 620470080, 1202160780 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..33.

FORMULA

G.f.: 1+sqrt((1+2x)/(1-2x))2x. - Michael Somos

PROG

(PARI) a(n)=if(n<2, max(0, n+1), 4*binomial(n-2, n\2-1))

CROSSREFS

2*A063886(n)=a(n+1).

Sequence in context: A135268 A245619 A131771 * A069753 A181245 A216950

Adjacent sequences:  A047070 A047071 A047072 * A047074 A047075 A047076

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified October 18 07:00 EDT 2018. Contains 316307 sequences. (Running on oeis4.)