A063271 Largest prime factor of 9^(2n)+1 (A063270).
2, 41, 193, 6481, 21523361, 42521761, 769, 647753, 926510094425921, 282429005041, 128653413121, 56625998353, 24127552321, 37644053098601, 36214795668330833, 42521761, 1716841910146256242328924544641, 3833564416504313, 56227703611393, 278733912072436804273
Offset: 0
Keywords
Links
- Daniel Suteu and Harry J. Smith, Table of n, a(n) for n = 0..172 (terms a(0)..a(50) from Harry J. Smith)
Programs
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Mathematica
Table[FactorInteger[9^(2n)+1][[-1,1]],{n,0,20}] (* Harvey P. Dale, Jan 07 2013 *) -
PARI
a(n)={vecmax(factor(9^(2*n) + 1)[,1])} \\ Harry J. Smith, Aug 20 2009
Formula
Extensions
Definition corrected by Harry J. Smith, Aug 20 2009