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A002590 Largest prime factor of 16^n + 1.
(Formerly M5046 N2180)
7
2, 17, 257, 241, 65537, 61681, 673, 15790321, 6700417, 38737, 4278255361, 2931542417, 22253377, 308761441, 54410972897, 4562284561, 67280421310721, 2879347902817, 487824887233, 24517014940753, 44479210368001, 88959882481 (list; graph; refs; listen; history; text; internal format)
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. 88.
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..280 (terms 0..256 from Sean A. Irvine, term 277 from Tyler Busby)
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) = A002587(4*n).
MATHEMATICA
Join[{1}, Table[FactorInteger[16^n+1][[-1, 1]], {n, 25}]] (* Harvey P. Dale, Feb 26 2012 *)
CROSSREFS
Sequence in context: A020561 A099702 A253549 * A029735 A291206 A037896
KEYWORD
nonn
AUTHOR
EXTENSIONS
More terms from Don Reble, Nov 14 2006
a(0) corrected by Sean A. Irvine, Apr 20 2014
STATUS
approved

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Last modified March 18 22:56 EDT 2024. Contains 370952 sequences. (Running on oeis4.)