OFFSET
1,2
COMMENTS
It appears that only 3628800 and 53094139822080000 have more than one representation. We have 3628800 = 10! = 6! * 7! and 53094139822080000 = 8! * 9! * 10! = 6! * 7! * 8! * 9!. - T. D. Noe, Jun 13 2012
LINKS
T. D. Noe, Table of n, a(n) for n = 1..1000
MATHEMATICA
Union[Reap[For[x1=1, x1 <= 14, x1++, x2=x1; a=x1!; While[a < 10^11, Sow[a]; x2 = x2+1; a = a*x2!]]][[2, 1]]] (* Jean-François Alcover, Jun 11 2012, after PARI *)
nn = 20; t = Range[nn]!; j = 2; While[i = 2; new = 0; While[p = Times @@ Take[t, {i, i + j - 1}]; p < t[[nn]], AppendTo[t, p]; new++; i++]; new > 0, j++]; t = Union[t] (* T. D. Noe, Jun 13 2012 *)
PROG
(PARI) l=listcreate(100)
for(x1=1, 14, x2=x1; a=x1!; while(a<1e11, listput(l, a); x2=x2+1; a=a*x2!))
listsort(l, 1); print(l)
/* Michael B. Porter, Mar 15 2010 */
CROSSREFS
KEYWORD
easy,nonn,nice
AUTHOR
STATUS
approved