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A002184 a(n) = least primitive factor of 2^(2n+1) - 1.
(Formerly M4400 N1855)
2
1, 7, 31, 127, 73, 23, 8191, 151, 131071, 524287, 337, 47, 601, 262657, 233, 2147483647, 599479, 71, 223, 79, 13367, 431, 631, 2351, 4432676798593, 103, 6361, 881, 32377, 179951, 2305843009213693951, 92737, 145295143558111, 193707721, 10052678938039, 228479, 439, 100801, 581283643249112959, 2687, 2593, 167 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

REFERENCES

J. Brillhart et al., Factorizations of b^n +- 1. Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 2nd edition, 1985; and later supplements.

M. Kraitchik, Recherches sur la Théorie des Nombres. Gauthiers-Villars, Paris, Vol. 1, 1924, Vol. 2, 1929, see Vol. 2, p. 84.

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

Max Alekseyev, Table of n, a(n) for n = 0..602

J. Brillhart et al., Factorizations of b^n +- 1, Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 3rd edition, 2002.

S. S. Wagstaff, Jr., The Cunningham Project

CROSSREFS

Cf. A002588.

Sequence in context: A181951 A218963 A125193 * A002588 A036280 A153005

Adjacent sequences:  A002181 A002182 A002183 * A002185 A002186 A002187

KEYWORD

nonn

AUTHOR

N. J. A. Sloane

EXTENSIONS

More terms from Don Reble, Nov 14 2006

STATUS

approved

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Last modified July 21 04:40 EDT 2019. Contains 325189 sequences. (Running on oeis4.)