

A076960


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


0




OFFSET

1,2


LINKS

Table of n, a(n) for n=1..9.


EXAMPLE

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


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 *)


CROSSREFS

Cf. A076959.
Sequence in context: A215793 A273279 A227851 * A298623 A035130 A055762
Adjacent sequences: A076957 A076958 A076959 * A076961 A076962 A076963


KEYWORD

nonn


AUTHOR

Amarnath Murthy, Oct 21 2002


EXTENSIONS

Corrected and extended by Emeric Deutsch, Jul 31 2005
2 further terms from Ryan Propper, Sep 11 2005
a(9) from Donovan Johnson, Mar 10 2010


STATUS

approved



