OFFSET
1,1
COMMENTS
All prime divisors of 1+4Q^2 are congruent to 1 modulo 4.
At least one prime divisor of 1+4Q^2 is congruent to 2 modulo 3 and hence to 5 modulo 12.
The first seven terms are the same as those of A057207.
The next term is known but is too large to include.
LINKS
Robert Price, Table of n, a(n) for n = 1..14
EXAMPLE
a(8) = 433361 is the smallest prime divisor congruent to 5 mod 12 of 1+4Q^2 = 3179238942812523869898723304484664524974766291591037769022962819805514576256901 = 13 * 433361 * 42408853 * 2272998442375593325550634821 * 5854291291251561948836681114631909089, where Q = 5 * 101 * 1020101 * 53 * 29 * 2507707213238852620996901 * 449.
MATHEMATICA
a={5}; q=1;
For[n=2, n<=5, n++,
q=q*Last[a];
AppendTo[a, Min[Select[FactorInteger[4*q^2+1][[All, 1]], Mod[#, 12]==5 &]]];
];
a (* Robert Price, Jul 16 2015 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Nick Hobson, Nov 18 2006 and Nov 23 2006
STATUS
approved