A109915 Product of all composite numbers k such that n<k<prime(r) where prime(r-1)<=n, or 1 if this set of k is empty.

1, 1, 4, 1, 6, 1, 720, 90, 10, 1, 12, 1, 3360, 240, 16, 1, 18, 1, 9240, 462, 22, 1, 11793600, 491400, 19656, 756, 28, 1, 30, 1, 45239040, 1413720, 42840, 1260, 36, 1, 59280, 1560, 40, 1, 42, 1, 91080, 2070, 46, 1, 311875200, 6497400, 132600, 2652

Offset

1,3

Comments

All terms that differ from 1 have the format A092435(i+1)/A092435(i). - R. J. Mathar, Aug 15 2007

Links

Table of n, a(n) for n=1..50.

Example

a(7) = 8*9*10 = 720.

Maple

A109915 := proc(n) local a, rm1, k; a := 1: rm1 := numtheory[pi](n) ; for k from n+1 to ithprime(rm1+1) do if not isprime(k) then a := a*k; fi; od: RETURN(a) ; end: seq(A109915(n), n=1..50) ; # R. J. Mathar, Aug 15 2007

Crossrefs

Cf. A109914.

Sequence in context: A032220 A032145 A032050 * A334467 A255198 A202521

Adjacent sequences: A109912 A109913 A109914 * A109916 A109917 A109918

Keyword

nonn

Author

Amarnath Murthy, Jul 16 2005

Extensions

Corrected and extended by R. J. Mathar, Aug 15 2007

Status

approved