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A274904
Largest prime factor of 6^n + 1.
6
2, 7, 37, 31, 1297, 101, 97, 197, 98801, 46441, 6781, 51828151, 1678321, 37571, 5030761, 1950271, 4709377, 12690943, 55117, 48713705333, 68754507401, 2527867231, 863017, 990000731, 473896897, 3655688315536801, 6291946695217, 883383463, 81035189089
OFFSET
0,1
LINKS
J. Brillhart et al., Factorizations of b^n +- 1, Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 3rd edition, 2002.
FORMULA
a(n) = A006530(A062394(n)). - Michel Marcus, Jul 11 2016
EXAMPLE
6^3 + 1 = 217 = 7*31, so a(3) = 31.
MATHEMATICA
Table[FactorInteger[6^n + 1][[-1, 1]], {n, 0, 40}]
PROG
(Magma) [Maximum(PrimeDivisors(6^n+1)): n in [0..40]];
CROSSREFS
Cf. similar sequences listed in A274903.
Sequence in context: A209251 A366670 A368398 * A173827 A029990 A042465
KEYWORD
nonn
AUTHOR
Vincenzo Librandi, Jul 11 2016
EXTENSIONS
Terms to a(100) in b-file from Vincenzo Librandi, Jul 12 2016
a(101)-a(408) in b-file from Amiram Eldar, Feb 02 2020
a(409)-a(420) in b-file from Max Alekseyev, Apr 25 2022, Aug 26 2023
STATUS
approved