

A157891


Number of natural numbers between exponents of successive Mersenne primes.


0



0, 1, 1, 5, 3, 1, 11, 29, 27, 17, 19, 393, 85, 671, 923, 77, 935, 1035, 169, 5265, 251, 1271, 8723, 1763, 1507, 21287, 41745, 24259, 21545, 84041, 540747, 102593, 398353, 140481, 1577951, 45155, 3951215, 6494323
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OFFSET

1,4


COMMENTS

a(0) = 0 since 2 is adjacent to 3 (exponent of 2nd Mersenne prime); a(2) = 1 since 4 is between 3 and 5 (exponent of 3rd Mersenne prime); a(3) = 1 since 6 is between 5 and 7 (exponent of 4th Mersenne prime); a(4) = 5 since 8, 9, 10, 11, and 12 are between 7 and 13 (exponent 5th Mersenne prime).


LINKS

Table of n, a(n) for n=1..38.


FORMULA

a(n) = (A000043(n+1)A000043(n))1. [From Jonathan Vos Post, Mar 09 2009]


CROSSREFS

Cf. A000027, A000043, A046933
Sequence in context: A021192 A074396 A229958 * A173644 A115991 A143410
Adjacent sequences: A157888 A157889 A157890 * A157892 A157893 A157894


KEYWORD

nonn


AUTHOR

Jani Melik, Mar 08 2009, Mar 09 2009


STATUS

approved



