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Search: id:A098555
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| A098555 |
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Least k such that k*Mersenne-prime(n)-1 is prime. |
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+0
3
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| 1, 2, 2, 6, 2, 14, 2, 90, 18, 80, 230, 80, 354, 84, 84, 1782, 450, 828, 2562, 2502, 6882, 9288, 890, 16022, 11088, 31034, 7272, 92372
(list; graph; listen)
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OFFSET
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1,2
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MATHEMATICA
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mexp = {the list in A000043}; f[n_] := Block[{k = 2, mp = 2^mexp[[n]] - 1}, While[ !PrimeQ[mp*k - 1] && k < 10000, k++ ]; If[k == 10000, 0, k]]; Do[ Print[ f[n]], {n, 22}] (from Robert G. Wilson v Sep 17 2004)
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CROSSREFS
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Cf. A000043, A000668, A098556.
Sequence in context: A071223 A055934 A096217 this_sequence A057562 A102628 A036655
Adjacent sequences: A098552 A098553 A098554 this_sequence A098556 A098557 A098558
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KEYWORD
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hard,nonn
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AUTHOR
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Pierre CAMI (pierrecami(AT)tele2.fr), Sep 14 2004
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EXTENSIONS
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More terms from Pierre CAMI (pierrecami(AT)tele2.fr), Jan 17 2005
a(1)=1, a(23)=890, a(27)=7272 corrected, other terms through a(28)=92372 verified by Ray Chandler (rayjchandler(AT)sbcglobal.net), Apr 16 2009
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