A051439 a(n) = prime(2^n + 1).

3, 5, 11, 23, 59, 137, 313, 727, 1621, 3673, 8167, 17881, 38891, 84047, 180511, 386117, 821647, 1742539, 3681149, 7754081, 16290073, 34136059, 71378603, 148948141, 310248251, 645155227, 1339484207, 2777105131, 5750079077

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn

Examples

			a(0) = prime(2^0+1) = prime(2) = 3,
a(1) = prime(2+1) = prime(3) = 5,
a(2) = prime(2^2+1) = prime(5) = 11,
a(3) = prime(2^3+1) = prime(9) = 23, and so on. - _N. J. A. Sloane_, Dec 09 2020
		

Links

• Hugo Pfoertner, Table of n, a(n) for n = 0..78, using David Baugh's b-file from A033844.
• Kim Walisch, Fast C++ prime counting function implementation.

Crossrefs

Cf. A000040, A033844, A018249, A051438, A051440.

Programs

Mathematica

Prime[2^Range[0,30]+1] (* Harvey P. Dale, Jan 19 2014 *)

Extensions

More terms from Michael Lugo (mlugo(AT)thelabelguy.com), Dec 22 1999