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A157891
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Number of natural numbers between exponents of successive Mersenne primes.
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0
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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
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1,4
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COMMENTS
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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).
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LINKS
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Table of n, a(n) for n=1..38.
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FORMULA
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a(n) = (A000043(n+1)-A000043(n))-1. [From Jonathan Vos Post, Mar 09 2009]
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CROSSREFS
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Cf. A000027, A000043, A046933
Sequence in context: A011363 A021192 A074396 * A173644 A115991 A143410
Adjacent sequences: A157888 A157889 A157890 * A157892 A157893 A157894
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KEYWORD
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nonn
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AUTHOR
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Jani Melik, Mar 08 2009, Mar 09 2009
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STATUS
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approved
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