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^3 = 2 iff i^3 - 2 has a prime factor > i; i is a solution mod p of x^3 = 2 iff p is a prime factor of i^3 - 2 and p > i. i^3 - 2 has at most two prime factors > i. For i such that i^3 - 2 has no prime factors > i; cf. A060591.
FORMULA
a(n) = n-th integer i such that i^3 - 2 has two prime factors > i.
EXAMPLE
a(3) = 20, since 20 is (after 7 and 16) the third integer i for which there are two primes p > i (viz. 31 and 43) such that i is a solution mod p of x^3 = 2, or equivalently, 20^3 - 2 = 7998 = 2*3*31*43 has two prime factors > 20. (cf. A059940).
CROSSREFS
KEYWORD
nonn
AUTHOR
Klaus Brockhaus, Apr 08 2001
STATUS
approved