A137389 a(n) = 2^prime(n) + 2^prime(n+1).

12, 40, 160, 2176, 10240, 139264, 655360, 8912896, 545259520, 2684354560, 139586437120, 2336462209024, 10995116277760, 149533581377536, 9147936743096320, 585467951558164480, 2882303761517117440, 149879795598890106880, 2508757194024499019776, 11805916207174113034240

Offset: 1

Author

Max Sills, Apr 10 2008

Keywords

• nonn
• easy

Examples

			a(3) = 160 because 2^5 + 2^7 = 160.
		

Crossrefs

Cf. A000040, A001043, A137781.

Programs

Maple

A137389:=n->2^ithprime(n)+2^ithprime(n+1): seq(A137389(n), n=1..20); # Wesley Ivan Hurt, Mar 27 2015

Mathematica

f[n_] := 2^Prime[n] + 2^Prime[n + 1]; Array[f, 18] (* Robert G. Wilson v *)
Table[2^Prime[n] + 2^Prime[n + 1], {n, 18}] (* Stefan Steinerberger, Apr 12 2008 *)

Formula

a(n) = A034785(n) + A034785(n+1). [R. J. Mathar, Jun 15 2009]

a(n) = 4*A137781(n). - Wesley Ivan Hurt, Mar 27 2015

Extensions

More terms from N. J. A. Sloane, Apr 10 2008