A191621 a(n) = ((n+1)^n-(n-1)^n)/2+1.

2, 5, 29, 273, 3377, 51013, 908609, 18640961, 432891137, 11225320101, 321504185345, 10079828372881, 343360783937537, 12627774819845669, 498676704524517377, 21046391759976988929, 945381827279671853057, 45032132922921758270917

Offset: 1

Author

Juri-Stepan Gerasimov, Jun 14 2011

Keywords

• nonn

Comments

The next prime in the sequence, after 2, 5 and 29, has at least 888 digits (n >= 349).

Examples

			a(1)=2 because ((1+1)^1-(1-1)^1)/2+1=2,
a(2)=5 because ((2+1)^2-(2-1)^2)/2+1=5,
a(3)=29 because ((3+1)^3-(3-1)^3)/2+1=29.
		

Programs

Mathematica

Table[((n+1)^n-(n-1)^n)/2+1,{n,20}] (* Harvey P. Dale, Oct 27 2019 *)