A128472 a(n) is the smallest prime of the form (2n-1)^k - 2 for k > (2n-1), or 0 if no such number exists.

0, 79, 6103515623, 5764799, 31381059607

Offset

1,2

Comments

a(6) = 11^22420 - 2 was found by Rick L. Shepherd on Sep 29 2007. It has 23349 decimal digits and it is too large to include.

a(7) through a(12): {771936328432730777189183517369830159827426282764863750131729657829597399846468418688727, 98526125335693359373, 339448671314611904643504117119, 37589973457545958193355599, 1136272165922724266740722458520499, 480250763996501976790165756943039}.

Links

Table of n, a(n) for n=1..5.

Henri Lifchitz and Renaud Lifchitz: PRP Records. Probable Primes Top 10000.

Crossrefs

Cf. A084714 (smallest prime of the form (2n-1)^k - 2).

Cf. A133856 (least number k > (2n-1) such that (2n-1)^k - 2 is prime).

Cf. A014224, A109080, A090669, A128455, A128457, A128458, A128459, A128460, A128461.

Cf. A133858, A133982.

Sequence in context: A265589 A116327 A060711 * A243432 A093404 A236236

Adjacent sequences: A128469 A128470 A128471 * A128473 A128474 A128475

Keyword

nonn

Author

Alexander Adamchuk, Mar 14 2007, Oct 01 2007

Extensions

Edited by Max Alekseyev, Sep 18 2009

Status

approved