A002185 Smallest primitive factor of 2^(2n+1) + 1. (Formerly M2233 N0885)

3, 1, 11, 43, 19, 683, 2731, 331, 43691, 174763, 5419, 2796203, 251, 87211, 59, 715827883, 67, 281, 1777, 22366891, 83, 2932031007403, 18837001, 283, 4363953127297, 307, 107, 2971, 571, 2833, 768614336404564651, 77158673929, 131, 7327657, 139, 56409643, 1753

Offset

0,1

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. 85.

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..560

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. A002589, A086257, A112927.

Sequence in context: A119908 A362996 A153257 * A002589 A048522 A365035

Adjacent sequences: A002182 A002183 A002184 * A002186 A002187 A002188

Keyword

nonn

Author

N. J. A. Sloane

Extensions

Terms a(25) onward from Max Alekseyev, Oct 16 2022

Status

approved