|
%I #13 Jun 24 2017 00:58:32
%S 6,85,928,2062427,391549471,5192879231
%N The count of primes between the n-th and (n+1)-st perfect number.
%F a(n) = A000720(A000396(n+1)) - A000720(A000396(n)).
%e a(1)=6 counts the 6 primes 7, 11, 13, 17, 19 and 23 between 6 and 28.
%e a(2)=85 counts the 85 primes 29, 31, ..., 487, 491 between 28 and 496.
%t PrimePi[Last[#]]-PrimePi[First[#]]&/@(Partition[(# (#+1))/2&/@ Select[ 2^Range[30]-1,PrimeQ],2,1]) (* _Harvey P. Dale_, Dec 27 2011 *)
%Y Cf. A000040, A000396.
%K nonn,hard
%O 1,1
%A _Juri-Stepan Gerasimov_, Aug 11 2009
%E Edited by _R. J. Mathar_, Aug 26 2009
%E More terms from _Harvey P. Dale_, Dec 27 2011
|
