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Search: id:A157894
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| A157894 |
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Number of composite numbers between exponents of successive Mersenne primes. |
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+0
1
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| 0, 1, 1, 4, 3, 1, 9, 23, 22, 14, 17, 327, 73, 576, 803, 67, 820, 908, 151, 4672, 222, 1141, 7827, 1583, 1352, 19255, 37986, 22155, 19704, 77081, 499295, 95038, 369638, 130508, 1469735, 42125, 3694547, 6091617
(list; graph; listen)
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OFFSET
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1,4
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COMMENT
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a(1) = 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 (expo nent of 4th Mersenne prime); a(4) = 4 since 8, 9, 10, and 12 are between 7 and 13 (exponent of 5 th Mersenne prime).
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MATHEMATICA
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mp={ (*A000043 *) }; lst = {}; Do[ c = mp[[n + 1]] - mp[[n]] - PrimePi@ mp[[n + 1]] + PrimePi@ mp[[n]]; AppendTo[lst, c], {n, 38}]; lst [From Robert G. Wilson v (rgwv(AT)rgwv.com), Mar 14 2009]
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CROSSREFS
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A002808, A000043, A046933
Sequence in context: A123160 A039758 A109692 this_sequence A128813 A109062 A112493
Adjacent sequences: A157891 A157892 A157893 this_sequence A157895 A157896 A157897
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KEYWORD
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nonn
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AUTHOR
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Jani Melik (jani.melik(AT)gmail.com), Mar 08 2009, Apr 02 2009
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EXTENSIONS
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a(34) - a(38) from Robert G. Wilson v (rgwv(AT)rgwv.com), Mar 14 2009
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