A261071 a(n) = 2^(n!) + 1.

3, 5, 65, 16777217, 1329227995784915872903807060280344577

Offset: 1

Author

Marco Ripà, Aug 08 2015

Keywords

• nonn
• easy

Comments

a(n) is a sum of two k-th powers of positive integers for k=1,2,...,n.

Examples

			a(3) = 2^6 + 1 = 65.
		

Crossrefs

Cf. A050923.

Programs

Magma

[2^(Factorial(n)) + 1: n in [1..6]]; // Vincenzo Librandi, Aug 09 2015

Mathematica

Array[2^#! + 1 &, 6] (* Paolo Xausa, Jan 31 2024 *)

PARI

first(m)=vector(m,i,2^(i!)+1); /* Anders Hellström, Aug 08 2015 */

Formula

a(n) = 2^(n!) + 1.

a(n) = A050923(n) + 1.