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%I #3 Mar 31 2012 10:24:25
%S 0,0,0,1,0,0,2,6,5,3,2,66,12,95,120,10,115,127,18,593,29,130,896,180,
%T 155,2032,3759,2104,1841,6960,41452,7555,28715
%N Number of primes between exponents of successive Mersenne primes.
%C a(6) = 0 since 17 is adjacent to 19 (exponent of 7th Mersenne prime); a(7) = 2 since 23 and 29 are between 19 and 31 (exponent of 8th Mersenne prime); a(8) = 6 since 37, 41, 43, 47, 53 and 59 are between 31 and 61 (exponent of 9th Mersenne prime)
%F a(n) = (PrimePi(A000043(n+1))-PrimePi(A000043(n)))-1 = (A000720(A000043(n+1))-A000720(A000043(n)))-1. [From _Jonathan Vos Post_, Mar 09 2009]
%Y Cf. A000040, A000043, A046933
%K nonn
%O 1,7
%A _Jani Melik_, Mar 08 2009, Mar 10 2009
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