OFFSET
1,4
COMMENTS
Every distinct prime dividing ((Product_{k=1..n-1} prime(k)) (mod prime(n))) also divides a(n).
Let Pn(n) = A002110(n) denote the primorial function. The number of natural numbers < Pn(n) that have prime(n+1) as a prime factor is equal to a(n). For example 19 numbers < Pn(4) = 210 have 11 as a prime factor. - Jamie Morken, Sep 18 2018
LINKS
Muniru A Asiru, Table of n, a(n) for n = 1..185
MAPLE
seq(floor(mul(ithprime(k), k=1..n-1)/ithprime(n)), n=1..20); # Muniru A Asiru, Sep 21 2018
MATHEMATICA
f[n_] := Floor[ Product[ Prime@k, {k, n - 1}] / Prime@n]; Array[f, 19] (* Robert G. Wilson v, Mar 07 2007 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Mar 07 2007
EXTENSIONS
More terms from Robert G. Wilson v, Mar 07 2007
STATUS
approved