A267288 Composites c where at least one base b with 1 < b < c exists such that b^(c-1) == 1 (mod c^2), i.e., composites c that are base-b 'Wieferich pseudoprimes' for at least one b between 1 and c.

133, 451, 561, 871, 904, 1065, 1105, 1267, 1729, 1891, 2059, 2201, 2501, 2821, 2993, 3145, 4641, 5005, 5551, 5841, 5963, 6409, 6541, 6601, 6697, 7107, 7471, 7501, 8321, 8323, 9637, 10585, 11266, 12209, 12403, 13571, 13585, 16471, 17261, 17466, 17770, 18103

Offset: 1

Author

Felix Fröhlich, Jan 12 2016

Keywords

• nonn

Comments

A002808(i) such that A256517(i) < A002808(i).

Any term is also a term of A039769.

Examples

			871 is a term of the sequence, since 699^870 == 1 (mod 871^2) and 699 < 871.
		

Crossrefs

Cf. A039769, A134307, A255885, A256517.

Programs

PARI

forcomposite(c=2, , for(b=2, c-1, if(Mod(b, c^2)^(c-1)==1, print1(c, ", "); break({1}))))