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A002234 Numbers k such that the Woodall number k*2^k - 1 is prime.
(Formerly M0820 N0311)
29
2, 3, 6, 30, 75, 81, 115, 123, 249, 362, 384, 462, 512, 751, 822, 5312, 7755, 9531, 12379, 15822, 18885, 22971, 23005, 98726, 143018, 151023, 667071, 1195203, 1268979, 1467763, 2013992, 2367906, 3752948, 17016602 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
a(34) = 17016602 is tentative until the range 16838832..17016601 is fully searched. - Eric W. Weisstein, Mar 22 2018
REFERENCES
J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 115, p. 40, Ellipses, Paris 2008.
F. Le Lionnais, Les Nombres Remarquables, Paris, Hermann, 1983, p. 95, 1983.
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
Ray Ballinger and Wilfrid Keller, Woodall numbers
C. K. Caldwell, Woodall Numbers
Brady Haran and Matt Parker, 383 is cool, Numberphile video (2017)
Matt Parker and Brady Haran, 383 and Woodall Primes, Numberphile video (2017)
H. Riesel, Lucasian criteria for the primality of N=h.2^n-1, Math. Comp., 23 (1969), 869-875.
Eric Weisstein's World of Mathematics, Woodall Number
Eric Weisstein's World of Mathematics, Integer Sequence Primes
PROG
(PARI) is(n)=isprime(n<<n - 1) \\ Charles R Greathouse IV, Feb 07 2017
CROSSREFS
Cf. A050918 (for the actual primes), A003261, A005849.
Sequence in context: A330030 A192441 A108326 * A074005 A145499 A221310
KEYWORD
nonn,nice,hard
AUTHOR
EXTENSIONS
a(27) communicated by Mohammed Bouayoun (bouyao(AT)wanadoo.fr), Mar 15 2004
a(28) = 1195203 found by M. Rodenkirch; contributed by Eric W. Weisstein, Nov 29 2005
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008
1467763, 2013992, 2367906, 3752948 from John Blazek, May 14 2009
a(34) = 17016602 communicated by Eric W. Weisstein, Mar 22 2018
STATUS
approved

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Last modified March 19 04:58 EDT 2024. Contains 370952 sequences. (Running on oeis4.)