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A181858 LCM(squares, factorials) / LCM(squares, swinging factorials) 1
1, 1, 1, 1, 1, 4, 4, 36, 18, 64, 576, 14400, 43200, 518400, 518400, 5080320, 12700800, 1625702400, 1625702400, 131681894400, 131681894400, 627056640000, 13168189440000, 1593350922240000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,6

COMMENTS

A divisibility sequence, i.e., if m|n then a(m)|a(n). Except for n = 9 the prime factors of A181858(n) are the primes <= floor((n-1)/2). Using this fact the divisibility property can be proved. - Peter Luschny, Jan 10 2011

LINKS

Table of n, a(n) for n=0..23.

Index to divisibility sequences

FORMULA

a(n) = A181857(n) / A181860(n).

MAPLE

A181858 := n -> `if`(n=0, 1, ilcm(n^2, n!)/ilcm(n^2, n!/iquo(n, 2)!^2));

PROG

(PARI) a(n)=lcm(n^2, n!)/lcm(n!/(n\2)!^2, n^2) \\ Charles R Greathouse IV, Feb 01 2013

CROSSREFS

Cf. A170826, A181860, A056040, A000290.

Sequence in context: A222504 A226008 A145109 * A227511 A249807 A180064

Adjacent sequences:  A181855 A181856 A181857 * A181859 A181860 A181861

KEYWORD

nonn

AUTHOR

Peter Luschny, Nov 21 2010

STATUS

approved

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Last modified May 24 09:23 EDT 2017. Contains 286963 sequences.