A177884 Pseudoprimes to base 2 of the form 4k+3.

1387, 2047, 4371, 8911, 13747, 14491, 19951, 42799, 60787, 90751, 123251, 150851, 256999, 258511, 271951, 272251, 275887, 294271, 387731, 396271, 422659, 435671, 443719, 452051, 476971, 514447, 672487, 680627, 741751, 769567, 877099, 916327, 1024651, 1052503, 1092547, 1152271, 1277179, 1302451, 1325843, 1397419, 1419607, 1433407, 1441091, 1459927

Offset: 1

Author

Juri-Stepan Gerasimov, Dec 14 2010

Keywords

• nonn

Comments

In at least the first 1801533 values (that is, for 2-pseudoprimes <10^15) of A001567, the entries of the form 4k+3 are less numerous than those of the form 4k+1. Is this always the case?

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A001567, A178723.

Programs

PARI

forstep(n=3,10^7,4,if(isprime(n),next());if(Mod(2,n)^(n-1)==1,print1(n,", ")))

Formula

A001567 INTERSECT A004767.

Extensions

Terms corrected by R. J. Mathar, Dec 17 2010