A062594 Numbers k such that 28^k - 27^k is prime.

3, 5, 19, 31, 257, 773

Offset: 1

Author

Mike Oakes, May 18 2001, May 19 2001

Keywords

• nonn
• hard

Comments

Terms > 1000 are often only strong pseudoprimes.

a(7) > 10^5. - Robert Price, Sep 04 2012

Crossrefs

Cf. A000043, A057468, A059801, A059802, A062572-A062666.

Programs

PARI

is(n)=ispseudoprime(28^n-27^n) \\ Charles R Greathouse IV, Jun 13 2017