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A002235
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Numbers n such that 3*2^n - 1 is prime.
(Formerly M0545 N0195)
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18
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0, 1, 2, 3, 4, 6, 7, 11, 18, 34, 38, 43, 55, 64, 76, 94, 103, 143, 206, 216, 306, 324, 391, 458, 470, 827, 1274, 3276, 4204, 5134, 7559, 12676, 14898, 18123, 18819, 25690, 26459, 41628, 51387, 71783, 80330, 85687, 88171, 97063, 123630, 155930, 164987, 234760, 414840, 584995, 702038, 727699, 992700, 1201046, 1232255, 2312734, 3136255
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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REFERENCES
| H. Riesel, Lucasian criteria for the primality of N=h.2^n-1, Math. Comp., 23 (1969), 869-875.
H. Riesel, ``Prime numbers and computer methods for factorization,'' Progress in Mathematics, Vol. 57, Birkhauser, Boston, 1985, Chap. 4, see pp. 381-384.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
| Wilfrid Keller, List of primes k.2^n - 1 for k < 300
C. K. Caldwell, The Prime Pages
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is prime
Eric Weisstein's World of Mathematics, Thabit ibn Kurrah Number
Eric Weisstein's World of Mathematics, Integer Sequence Primes
Mersenne Forum, 321 Search
Eric Weisstein's World of Mathematics, Integer Sequence Primes
Eric Weisstein's World of Mathematics, Thabit ibn Kurrah Number
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MATHEMATICA
| lst={}; Do[If[PrimeQ[3*2^n-1], Print[n]; AppendTo[lst, n]], {n, 10^5}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Aug 21 2008]
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CROSSREFS
| Cf. A000043, A007505, A003307, A046865, A079906, A046866, A001771, A005541, A056725, A046867, A079907.
Sequence in context: A130690 A074885 A091336 * A030705 A057128 A018534
Adjacent sequences: A002232 A002233 A002234 * A002236 A002237 A002238
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KEYWORD
| nonn,nice
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| More terms from Eric Weisstein (eric(AT)weisstein.com), Sep 29 2007
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