A212792 Product of all primes in the interval ((n+1)/2,n].

1, 2, 3, 3, 5, 5, 35, 35, 7, 7, 77, 77, 143, 143, 143, 143, 2431, 2431, 46189, 46189, 4199, 4199, 96577, 96577, 7429, 7429, 7429, 7429, 215441, 215441, 6678671, 6678671, 392863, 392863, 392863, 392863, 765049, 765049, 765049, 765049, 31367009, 31367009, 1348781387

Offset: 1

Author

Stanislav Sykora, May 27 2012

Keywords

• nonn

Comments

The case n=1 is special and defined conventionally.

a(n) = A034386(n)/A034386(1+floor((n+1)/2)).

Notice that the interval is semiopen; a prime p is included in the product if (n+1)<2p<=2n.

Examples

			a(13) = product of all primes in (7,13] = 11*13 = 143.
		

Links

• Stanislav Sykora, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A212791, A034386.

Programs

PARI

{p2(n) = result=1;forprime(p=1+floor((n+1)\2),n,result=result*p);}