A137666 Largest prime factor of A137664(n) = (p + 1)^p - 1 for p = prime(n).

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 *)

Crossrefs

Cf. A128452, A128456, A128356, A128357, A137664, A137665, A128466, A127837.

Sequence in context: A260967 A367788 A128456 * A137665 A128466 A048122

Adjacent sequences: A137663 A137664 A137665 * A137667 A137668 A137669

Keyword

hard,nonn

Author

Alexander Adamchuk, Feb 04 2008

Status

approved