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A137666
Largest prime factor of A137664(n) = (p + 1)^p - 1 for p = prime(n).
3
2, 7, 311, 337, 266981089, 29914249171, 7563707819165039903, 192696104561, 58769065453824529, 847499019384726257346113954958447091, 18158209813151, 138233050898929517126243814850350442620694127
OFFSET
1,1
COMMENTS
a(n) is also the largest prime factor of A137665(n) = A137664(n)/prime(n)^2. p^2 divides A137664(n) = (p + 1)^p - 1, p = prime(n). Least prime factors of A137664(n) are listed in A128456.
a(n) = A128456(n) = A137665(n) = ((p + 1)^p - 1)/p^2 for n = {1,2,3,7,595,...} corresponding to p = prime(n) = {2,3,5,17,4357,...} = A127837.
LINKS
Jens Kruse Andersen, Table of n, a(n) for n = 1..26
MATHEMATICA
FactorInteger[#][[-1, 1]]&/@((#+1)^#-1&/@Prime[Range[12]]) (* Harvey P. Dale, Apr 07 2018 *)
KEYWORD
hard,nonn
AUTHOR
Alexander Adamchuk, Feb 04 2008
STATUS
approved