login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual appeal: Please make a donation to keep the OEIS running! Over 6000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified November 21 16:08 EST 2017. Contains 295003 sequences.