1,1

292 = 100100100, 438 = 110110110, 546 = 001000100010, 1092 = 010001000100, 1170 = 010010010010, 2340 = 100100100100, 3510 = 110110110110.

According to Dobson, all primes where m is of the form 2*(4^(r/2)-1)/3 cannot be Wieferich primes.

Triples (m, r, s) producing the terms through the formula in definition are (4, 3, 3), (6, 3, 3), (2, 4, 3), (4, 4, 3), (2, 3, 4), (4, 3, 4), (6, 3, 4).

Table of n, a(n) for n=1..7.

S. Agou, Irréductibilité des polynômes f(X^p^r-aX) sur un corps fini F_p^s, J. reine angew. Mat. 292 (1977), 191-195.

J. B. Dobson, A note on the two known Wieferich primes (Archive of the site from August 28 2011)

Cf. A001220, A242139.

Sequence in context: A155140 A248210 A142284 * A252409 A251682 A251675

Adjacent sequences: A245580 A245581 A245582 * A245584 A245585 A245586

nonn,more

Felix Fröhlich, Jul 26 2014

approved