OFFSET
0,2
COMMENTS
For n > 0, 2^(a(n)-2n-2) == 1 (mod a(n)), since 2^(a(n)-1) == 2^(2n+1) == 1 (mod a(n)). - Thomas Ordowski, Aug 11 2021
a(n) == 1 (mod 2n+1). - Thomas Ordowski, Aug 11 2021
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
FORMULA
a(n) = A112927(2n+1). - Max Alekseyev, Apr 26 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
More terms from Don Reble, Nov 14 2006
STATUS
approved