A023593 Exponent of least prime factor of 2*prime(n)+1.

1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 2, 1, 1, 2, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 3, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 4, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 3, 1, 1, 1, 1

Offset: 1

Author

Clark Kimberling

Keywords

• nonn

Examples

			a(6) = 3 because 2*prime(6)+1 = 27 = 3^3.
		

Crossrefs

Cf. A067029, A072055.

Programs

Maple

A023593 := proc(n)
    A067029(2*ithprime(n)+1) ;
end proc: # R. J. Mathar, Jul 08 2015

Mathematica

Table[FactorInteger[2*Prime[n] + 1][[1]][[2]], {n, 100}] (* Clark Kimberling, Oct 01 2013 *)

Extensions

Corrected by Clark Kimberling, Oct 01 2013