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A241543 a(n) = A241477(n, n). 4
1, 1, 2, 2, 2, 6, 4, 20, 10, 70, 28, 252, 84, 924, 264, 3432, 858, 12870, 2860, 48620, 9724, 184756, 33592, 705432, 117572, 2704156, 416024, 10400600, 1485800, 40116600, 5348880, 155117520, 19389690, 601080390, 70715340, 2333606220, 259289580, 9075135300 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

See A241477 and A232500 for the combinatorial definitions.

LINKS

Table of n, a(n) for n=0..37.

FORMULA

a(n) = 2*floor(n/2)*(n-2)!/floor(n/2)!^2 for n>=2.

a(n+2) = 2*A057977(n) for n>=0. - Peter Luschny, Jul 17 2016

MAPLE

A241543 := proc(n)

    if n < 2 then 1

  else 2*iquo(n, 2)*(n-2)!/iquo(n, 2)!^2

    fi end:

seq(A241543(n), n=0..37);

CROSSREFS

Cf. A057977, A241477, A232500.

Sequence in context: A246707 A324339 A211391 * A210740 A209820 A145890

Adjacent sequences:  A241540 A241541 A241542 * A241544 A241545 A241546

KEYWORD

nonn

AUTHOR

Peter Luschny, Apr 25 2014

STATUS

approved

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Last modified June 20 05:01 EDT 2019. Contains 324229 sequences. (Running on oeis4.)