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A074249 a(n) = largest prime factor of 7^n-1. 12
3, 3, 19, 5, 2801, 43, 4733, 1201, 1063, 2801, 293459, 181, 16148168401, 4733, 159871, 169553, 2767631689, 117307, 4534166740403, 4021, 11898664849, 10746341, 31479823396757, 1201, 31280679788951, 16148168401, 2583253 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
a(n) = A006530(A024075(n)). - Michel Marcus, Dec 16 2017
MATHEMATICA
Join[{1}, Table[FactorInteger[7^n - 1] [[-1, 1]], {n, 30}]] (* Vincenzo Librandi, Aug 23 2012 *)
PROG
(PARI) a(n) = vecmax(factor(7^n-1)[, 1]); \\ Michel Marcus, Dec 16 2017
CROSSREFS
Sequence in context: A096935 A136475 A143180 * A234018 A101617 A131443
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Sep 26 2002
EXTENSIONS
More terms from Benoit Cloitre, Sep 29 2002
Terms to a(80) in b-file from Vincenzo Librandi, Aug 23 2013
a(81)-a(378) in b-file from Amiram Eldar, Feb 02 2020
a(0) removed and a(379)-a(388) in b-file added by Max Alekseyev, Apr 25 2022, Sep 11 2022
STATUS
approved

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Last modified April 23 05:59 EDT 2024. Contains 371906 sequences. (Running on oeis4.)