A183071 Positive integers k such that each prime divisor of 2^k - 1 has the form 4j + 3.

1, 2, 3, 5, 6, 7, 10, 13, 14, 15, 17, 19, 26, 30, 31, 34, 38, 43, 51, 61, 62, 65, 79, 85, 86, 89, 93, 95, 107, 122, 127, 129, 130, 133, 158, 170, 193, 254, 255, 301, 311, 331, 349, 389, 445, 521, 557, 577, 579, 607, 631, 647, 1103, 1167

Offset: 1

Author

Stuart Clary, Dec 23 2010

Keywords

• nonn

Comments

The exponents of the Mersenne primes (A000043) are contained in this sequence.

Needed factorizations are in the Cunningham Project.

Examples

			6 is in this sequence because 2^6 - 1 = 3^2 * 7, and 3 and 7 have the form 4j + 3.
		

Links

• S. S. Wagstaff, Jr., The Cunningham Project.

Crossrefs

Cf. A000043, A136003, A183072, A183073, A183074.

Cf. A000668, A136005, A183075, A183076, A183077, A183078.

Formula

A183075(n) = 2^a(n) - 1.

Extensions

a(53)-a(54) from Amiram Eldar, Feb 18 2019