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A163844 Row sums of triangle A163841. 1
1, 5, 25, 125, 621, 3065, 15051, 73645, 359485, 1752125, 8532591, 41537105, 202200415, 984526275, 4795673085, 23372376525, 113978687085, 556205251325, 2716129289775 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

a(n) = sum{k=0..n} sum{i=k..n} binomial(n-k,n-i)*(2i)$

where i$ denotes the swinging factorial of i (A056040).

LINKS

Table of n, a(n) for n=0..18.

Peter Luschny, Swinging Factorial.

MAPLE

swing := proc(n) option remember; if n = 0 then 1 elif

irem(n, 2) = 1 then swing(n-1)*n else 4*swing(n-1)/n fi end:

a := proc(n) local i, k; add(add(binomial(n-k, n-i)*swing(2*i), i=k..n), k=0..n) end:

CROSSREFS

Cf. A163841.

Sequence in context: A269490 A269772 A269652 * A250357 A216125 A057831

Adjacent sequences:  A163841 A163842 A163843 * A163845 A163846 A163847

KEYWORD

nonn

AUTHOR

Peter Luschny, Aug 06 2009

STATUS

approved

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Last modified May 23 16:25 EDT 2017. Contains 286925 sequences.