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A264137 Largest prime factor of the n-th Pell number, A000129(n). 4
2, 5, 3, 29, 7, 13, 17, 197, 41, 5741, 11, 33461, 239, 269, 577, 8297, 199, 179057, 59, 45697, 5741, 982789, 1153, 29201, 33461, 146449, 337, 44560482149, 269, 3272609, 665857, 52734529, 15607, 1800193921, 199, 1101341, 9369319, 4605197, 5521, 1746860020068409 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

COMMENTS

First differs from A246556 at n = 17. Since Pell(17) = 1136689 = 137 * 8297, we find that 137 does not divide any earlier Pell number, and hence A246556(17) = 137, but 8297 is also prime, and so a(17) = 8297.

LINKS

Jon E. Schoenfield, Table of n, a(n) for n = 2..240

FORMULA

a(n) = A006530(A000129(n)).

MATHEMATICA

Table[FactorInteger[Fibonacci[n, 2]][[-1, 1]], {n, 25}] (* Alonso del Arte, Dec 10 2016 *)

FactorInteger[#][[-1, 1]]&/@LinearRecurrence[{2, 1}, {2, 5}, 60] (* Harvey P. Dale, Jun 08 2019 *)

CROSSREFS

Cf. A000129, A006530, A060385, A246556.

Sequence in context: A122992 A051497 A246556 * A308949 A109734 A239309

Adjacent sequences:  A264134 A264135 A264136 * A264138 A264139 A264140

KEYWORD

nonn

AUTHOR

Jon E. Schoenfield, Dec 29 2015

STATUS

approved

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Last modified July 7 15:31 EDT 2020. Contains 335495 sequences. (Running on oeis4.)