OFFSET
1,1
COMMENTS
Terms > 1000 are often only strong pseudoprimes.
a(5) > 10^5 - Robert Price, Nov 14 2012
PROG
(PARI) is(n)=ispseudoprime(31^n-30^n) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
KEYWORD
nonn,hard
AUTHOR
Mike Oakes, May 18 2001, May 19 2001
STATUS
approved