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

2, 19, 769, 773, 4507, 26183

Offset

1,1

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

Links

Table of n, a(n) for n=1..6.

Prog

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

Crossrefs

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

Sequence in context: A300995 A086976 A118189 * A155956 A013047 A012951

Adjacent sequences: A062620 A062621 A062622 * A062624 A062625 A062626

Keyword

nonn,hard

Author

Mike Oakes, May 18 2001, May 19 2001

Extensions

a(6) from Robert Price, Dec 06 2012

Status

approved