A062623 Numbers k such that 57^k - 56^k is prime.

2, 19, 769, 773, 4507, 26183

Offset: 1

Author

Mike Oakes, May 18 2001, May 19 2001

Keywords

• nonn
• hard

Comments

Terms greater than 1000 often correspond only to strong pseudoprimes. [Clarified by M. F. Hasler, Sep 15 2013]

a(7) > 10^5. - Robert Price, Dec 06 2012

Crossrefs

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

Programs

PARI

is(n)=ispseudoprime(57^n-56^n) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(6) from Robert Price, Dec 06 2012