A020307 Strong pseudoprimes to base 81.
91, 121, 511, 671, 703, 949, 1387, 1541, 1729, 1891, 2701, 2821, 3281, 3367, 3751, 5551, 6643, 7381, 8401, 8695, 8911, 10585, 11011, 12403, 12991, 14383, 15203, 15251, 15841, 15863, 16471, 16531, 18721, 19345, 23521, 24661, 24727, 26335, 28009, 29341
Offset: 1