OFFSET
1,1
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) = A074477(2*n). - Amiram Eldar, Feb 02 2020
EXAMPLE
9^4 - 1 = 6560 = 2^5*5*41, so a(4) = 41.
MATHEMATICA
Table[FactorInteger[9^n-1][[-1, 1]], {n, 40}]
PROG
(Magma) [Maximum(PrimeDivisors(9^n-1)): n in [1..40]];
CROSSREFS
KEYWORD
nonn
AUTHOR
Vincenzo Librandi, Jul 11 2016
EXTENSIONS
Terms to a(100) in b-file from Vincenzo Librandi, Jul 13 2016
a(101)-a(330) in b-file from Amiram Eldar, Feb 02 2020
a(331)-a(691) in b-file from Max Alekseyev, May 22 2022, Jul 25 2023
STATUS
approved