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
Examples
a(2) = 8 as pi(24) = 9 and pi(2) = 1.
Programs
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Maple
with(numtheory): 0,seq(pi((2*n)!)-pi(n!),n=2..5); # Emeric Deutsch, Jul 31 2005
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Mathematica
a[n_] := PrimePi[(2n)! - 1] - PrimePi[n! ]; Table[a[n], {n, 1, 8}] (* Ryan Propper, Sep 11 2005 *)
Formula
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