A211456 Smallest base b for which A181780(n) is a Fermat pseudoprime.

4, 8, 7, 9, 10, 6, 14, 8, 18, 16, 9, 21, 20, 8, 8, 25, 22, 11, 26, 45, 34, 4, 28, 3, 32, 39, 10, 8, 38, 65, 24, 8, 50, 3, 40, 5, 57, 44, 61, 8, 26, 46, 12, 12, 50, 121, 8, 23, 61, 52, 22, 23, 19, 37, 49, 24, 49, 58, 62, 6, 97, 67, 55, 11, 14, 165, 68, 57, 9

Offset: 1

Author

T. D. Noe, Apr 13 2012

Keywords

• nonn

Comments

That is, the smallest b for which b^(s-1) = 1 (mod s), where s is in A181780.

Links

• T. D. Noe, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A181780, A211455, A211457, A211458.

Programs

Mathematica

t = {}; n = 1; While[Length[t] < 100, n++; If[! PrimeQ[n], s = Select[Range[2, n-2], PowerMod[#, n-1, n] == 1 &]; If[s != {}, AppendTo[t, {n, Length[s], s}]]]]; First/@Transpose[t][[3]]