A141061 - OEIS

%I #7 Mar 04 2014 23:50:24

%S 2,3,3,7,5,9,6,10,15,7,18,13,11,16,20,22,16,21,18,19,28,22,29,39,21,

%T 23,25,17,31,69,28,40,23,56,24,45,42,38,48,45,30,64,30,46,29,88,82,44,

%U 33,42,60,40,81,59,60,69,39,64,49,42,95,110,59,47,56,134,70,106,49,55,77

%N Number of primes between n*p(n) and (n+1)*p(n+1), where p(n) is the n-th prime.

%e a(4)=7 because between 4*p(4)=4*7=28 and 5*p(5)=5*11=55 one has 7 primes (29,31,37,41,43,47 and 53).

%p with(numtheory): seq(pi((n+1)*ithprime(n+1))-pi(n*ithprime(n)), n=1..74); # _Emeric Deutsch_, Aug 16 2008

%K nonn

%O 1,1

%A _Juri-Stepan Gerasimov_, Aug 04 2008

%E Corrected and extended by _Emeric Deutsch_, Aug 16 2008