A076960 a(n) is the number of primes between n! and (2n)!.

0, 8, 125, 4222, 258659, 25306159, 3610490130, 706003793908, 181035032176791, 58893601709293849, 23688535118130027712, 11539922212278290441881

Offset: 1

Author

Amarnath Murthy, Oct 21 2002

Keywords

• nonn
• more

Examples

			a(2) = 8 as pi(24) = 9 and pi(2) = 1.
		

Crossrefs

Cf. A003604, A076959.

Programs

Maple

with(numtheory): 0,seq(pi((2*n)!)-pi(n!),n=2..5); # Emeric Deutsch, Jul 31 2005

Mathematica

a[n_] := PrimePi[(2n)! - 1] - PrimePi[n! ]; Table[a[n], {n, 1, 8}] (* Ryan Propper, Sep 11 2005 *)

Formula

a(n) = A003604(2*n) - A003604(n), for n >= 2. - Amiram Eldar, Jun 11 2024

Extensions

Corrected and extended by Emeric Deutsch, Jul 31 2005

a(7)-a(8) from Ryan Propper, Sep 11 2005

a(9) from Donovan Johnson, Mar 10 2010

a(10)-a(12) from Amiram Eldar, Jun 11 2024