OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..420 (terms 1..100 from Vincenzo Librandi)
J. Brillhart et al., Factorizations of b^n +- 1, Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 3rd edition, 2002.
FORMULA
EXAMPLE
6^5 - 1 = 7775 = 5*5*311, so a(5) = 311.
MATHEMATICA
Table[FactorInteger[6^n - 1][[-1, 1]], {n, 40}]
PROG
(Magma) [Maximum(PrimeDivisors(6^n-1)): n in [1..40]];
(PARI) a(n) = vecmax(factor(6^n-1)[, 1]); \\ Michel Marcus, Jul 13 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Vincenzo Librandi, Jul 11 2016
STATUS
approved