Number of primes between exponents of successive Mersenne primes.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =0a(5) =0a(6) =2a(7) =6a(8) =5a(9) =3a(10) =2a(11) =66a(12) =12a(13) =95a(14) =120a(15) =10a(16) =115a(17) =127a(18) =18a(19) =593a(20) =29a(21) =130a(22) =896a(23) =180a(24) =155a(25) =2032a(26) =3759a(27) =2104a(28) =1841a(29) =6960