

A096123


Least product n*(n1)*(n2)*...*(nk+1) divisible by (nk)!.


3



1, 2, 6, 12, 60, 120, 840, 1680, 15120, 5040, 55440, 665280, 8648640, 17297280, 259459200, 518918400, 8821612800, 17643225600, 335221286400, 670442572800, 14079294028800, 28158588057600, 647647525324800, 1295295050649600
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OFFSET

1,2


COMMENTS

Conjecture: a(n) = n!/(p1)! for all sufficiently large n, where p is the least prime such that n <= 2*p (Amarnath Murthy). A096974 gives numbers n such that a(n) = n!/(nextprime(n/2)1)! and indicates that this conjecture is most probably false.


LINKS

Table of n, a(n) for n=1..24.


EXAMPLE

a(10) = 5040 as 10*9 is not divisible by 8!, 10*9*8 is not divisible by 7! but 10*9*8*7 = 5040 is divisible by 6! = 720.


PROG

(PARI) {for(n=1, 24, p=1; k=0; b=1; while(b&&k<n, p=p*(nk); d=(nk)!; if(p%d==0, b=0; print1(p, ", "), k++)))}


CROSSREFS

Cf. A056042, A096974.
Sequence in context: A185021 A191836 A072486 * A081125 A138570 A161887
Adjacent sequences: A096120 A096121 A096122 * A096124 A096125 A096126


KEYWORD

nonn


AUTHOR

Amarnath Murthy, Jul 01 2004


EXTENSIONS

Edited and extended by Klaus Brockhaus, Jul 17 2004


STATUS

approved



