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A182923 n$ / A055773(n), where n$ denotes the swinging factorial (A056040). 1
1, 1, 1, 1, 2, 2, 4, 4, 2, 18, 36, 36, 12, 12, 24, 360, 90, 90, 20, 20, 4, 84, 168, 168, 28, 700, 1400, 37800, 5400, 5400, 720, 720, 90, 2970, 5940, 207900, 23100, 23100, 46200, 1801800, 180180, 180180, 17160 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

COMMENTS

a(n) = n$ * P(floor(n/2))/P(n), P(n) primorial number A034386.

A182922(n) / A182923(n) = A000142(n) / A056040(n) = A180064(n).

LINKS

Table of n, a(n) for n=0..42.

MAPLE

swingfact := n -> n! / iquo(n, 2)!^2;

A182923 := n -> swingfact(n) / mul(k, k=select(isprime, [$iquo(n, 2)+1..n])):

CROSSREFS

Cf. A182922, A034386, A055773, A180064.

Sequence in context: A128442 A290633 A038674 * A263856 A090277 A024222

Adjacent sequences:  A182920 A182921 A182922 * A182924 A182925 A182926

KEYWORD

nonn

AUTHOR

Peter Luschny, Mar 05 2011

STATUS

approved

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Last modified October 23 04:19 EDT 2018. Contains 316519 sequences. (Running on oeis4.)