OFFSET
1,1
COMMENTS
Solutions mod p are represented by integers from 0 to p-1. The following equivalences holds for i > 1: There is a prime p such that i is a solution mod p of x^2 = 2 iff i^2-2 has a prime factor > i; i is a solution mod p of x^2 = 2 iff p is a prime factor of i^2-2 and p > i.
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
FORMULA
Integer i > 1 is a term of this sequence iff i^2-2 has no prime factor > i.
EXAMPLE
a(1) = 2, since there is no prime p such that 2 is a solution mod p of x^2 = 2. a(2) = 10, since there is no prime p such that 10 is a solution mod p of x^2 = 2 and for each integer i from 3 to 9 there is a prime q such that i is a solution mod q of x^2 = 2 (cf. A059772).
MAPLE
select(t -> max(numtheory:-factorset(t^2-2)) <= t, [$2..1000]); # Robert Israel, Feb 23 2016
PROG
(PARI) is(n)=my(f=factor(n^2-2)[, 1]); n>1&&f[#f]<=n \\ Charles R Greathouse IV, Aug 24 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Klaus Brockhaus, Mar 24 2001
STATUS
approved