1,4

Also product of composite numbers less than or equal to n. - Benoit Cloitre (benoit7848c(AT)orange.fr), Aug 18 2002

Also, except for the first term, n! divided by n primorial (or n!/n#). - Cino Hilliard (hillcino368(AT)gmail.com), Mar 26 2006

Comment from Alexander R. Povolotsky (pevnev(AT)juno.com) and Peter J. C. Moses (mows(AT)mopar.freeserve.co.uk), Aug 27 2007: It appears that a(n) = smallest positive number m such that the sequence b(n) = { m (i^1 + 1!) (i^2 + 2!) ... (i^n + n!) / n! : i >= 0 } takes integral values. [It would be nice to have a proof of this! - N. J. A. Sloane (njas(AT)research.att.com)] Cf. A064808 (for n=2), A131682 (for n=3), A131683 (for n=4), A131527 (for n=5), A131684 (for n=6), A131528. See also A129995, A131685.

It appears that every term > 4 is divisible by 3 - Alexander R. Povolotsky (pevnev(AT)juno.com), Oct 18 2007

T. D. Noe, Table of n, a(n) for n=1..100

Index entries for sequences related to factorial numbers

a(n) = A000142(n)/A034386(n).

n=11: 11!=39916800=2310*17280 and 2310=2*3*5*7*11

Table[n! / Product[ Prime[i], {i, 1, PrimePi[n]}], {n, 1, 24}]

(PARI) a(n)=prod(i=1, n, i^if(isprime(i), 0, 1))

Cf. A000142, A002110, A003418, A034386, A045948, A048148, A036691.

Sequence in context: A075219 A088304 A131978 this_sequence A058166 A092897 A117429

Adjacent sequences: A049611 A049612 A049613 this_sequence A049615 A049616 A049617

nonn

Labos E. (labos(AT)ana.sote.hu)

Edited by N. J. A. Sloane (njas(AT)research.att.com), Oct 07 2007