login
A002235
Numbers m such that 3*2^m - 1 is prime.
(Formerly M0545 N0195)
38
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
OFFSET
1,3
REFERENCES
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).
LINKS
Jeppe Stig Nielsen, Table of n, a(n) for n = 1..64
Mersenne Forum, 321 Search
H. Riesel, Lucasian criteria for the primality of N=h.2^n-1, Math. Comp., 23 (1969), 869-875.
H. Riesel, Lucasian criteria for the primality of N=h.2^n-1, Math. Comp., 23 (1969), 869-875. [Annotated scanned copy]
Eric Weisstein's World of Mathematics, Integer Sequence Primes
Eric Weisstein's World of Mathematics, Thabit ibn Kurrah Prime
Eric Weisstein's World of Mathematics, Thabit ibn Kurrah Rule
MATHEMATICA
lst={}; Do[If[PrimeQ[3*2^n-1], Print[n]; AppendTo[lst, n]], {n, 10^5}]; lst (* Vladimir Joseph Stephan Orlovsky, Aug 21 2008 *)
PROG
(PARI) is(n)=ispseudoprime(3<<n - 1) \\ Charles R Greathouse IV, Aug 27 2014
KEYWORD
nonn,nice
EXTENSIONS
More terms from Eric W. Weisstein, Sep 29 2007
a(60) = 11484018 from The Prime Pages, from Pierre CAMI, Nov 25 2014
a(61)-a(62) from The Prime Pages, from Eric W. Weisstein, Nov 03 2015
Terms moved from Data to b-file, and more terms added to b-file, by Jeppe Stig Nielsen, Sep 07 2021
STATUS
approved