OFFSET
1,2
COMMENTS
This function is very useful in a problem due to Paul Erdős recorded in A157017. - M. F. Hasler, Feb 26 2014
FORMULA
MATHEMATICA
nn=20; With[{comps=Complement[Range[2nn], Prime[Range[PrimePi[2nn]]]]}, Table[ Times@@ Select[comps, #>n&&#<=2n&], {n, nn}]] (* Harvey P. Dale, Feb 18 2013 *)
PROG
(PARI) a(n)=prod(i=n+1, 2*n, if(isprime(i), 1, i))
CROSSREFS
KEYWORD
nonn
AUTHOR
Jaume Oliver Lafont, Mar 03 2009
STATUS
approved