A139480 a(n) = A000043(n) - 3.

0, 2, 4, 10, 14, 16, 28, 58, 86, 104, 124, 518, 604, 1276, 2200, 2278, 3214, 4250, 4420, 9686, 9938, 11210, 19934, 21698, 23206, 44494, 86240, 110500, 132046, 216088, 756836, 859430, 1257784, 1398266, 2976218, 3021374, 6972590, 13466914, 20996008, 24036580, 25964948

Offset: 2

Author

Artur Jasinski, Apr 22 2008

Keywords

• nonn

Comments

2^a(n)-1 is divisible by 3. For (2^a(n)-1)/3 see A124477.

For a(n)/2 see A139481.

Links

• Amiram Eldar, Table of n, a(n) for n = 2..48

Crossrefs

Cf. A000043, A000668, A124477, A139479, A139481.

Programs

Mathematica

MersennePrimeExponent[Range[2, 48]] - 3 (* Amiram Eldar, Oct 17 2024 *)

Extensions

Definition corrected by Omar E. Pol, May 23 2008

Edited by N. J. A. Sloane, May 23 2008

a(40)-a(42) from Amiram Eldar, Oct 17 2024