A110808 Least factorial obtained as n(n-1)...(n-k).

1, 2, 6, 24, 120, 6, 5040, 40320, 362880, 720, 39916800, 479001600, 6227020800, 87178291200, 1307674368000, 20922789888000, 355687428096000, 6402373705728000, 121645100408832000, 2432902008176640000

Offset

1,2

Comments

Max (a(n)) = n!. a(n!) = n!. Define numbers of the type 10 as factoriable numbers. Are there any more such numbers? i.e. numbers of the type k such that a(k) is neither k nor k!.

Links

Table of n, a(n) for n=1..20.

Example

a(10) = 10*9*8 = 720.
a(6) = 6.

Maple

isfact := proc(n) local i ; for i from 1 do if i! = n then RETURN(true) ; elif i! > n then RETURN(false) ; fi ; od; end: A110808 := proc(n) local k, nfall ; for k from 0 do nfall := mul(n-i, i=0..k) ; if isfact(nfall) then RETURN(nfall) ; fi ; od: end: seq(A110808(n), n=1..40) ; # R. J. Mathar, Feb 08 2008

Crossrefs

Sequence in context: A358611 A362332 A092495 * A369407 A284567 A360300

Adjacent sequences: A110805 A110806 A110807 * A110809 A110810 A110811

Keyword

nonn

Author

Amarnath Murthy, Aug 14 2005

Extensions

More terms from R. J. Mathar, Feb 08 2008

Status

approved