A076793 a(n) = Sum_{k=1..n} 2^prime(k).

0, 4, 12, 44, 172, 2220, 10412, 141484, 665772, 9054380, 545925292, 2693408940, 140132362412, 2339155617964, 11135248640172, 151872736995500, 9159071991736492, 585619824295159980, 2891462833508853932, 150465415423185266860, 2511648656858007873708

Offset: 0

Author

Walter Carlini, Nov 17 2002

Keywords

• easy
• nonn

Comments

a(468) has 1000 decimal digits. - Michael De Vlieger, Jul 14 2017

Examples

			a(1) = 2^prime(1) = 2^2 = 4; a(2) = 4 + 2^prime(2) = 4 + 2^3 = 12.
		

Links

• Michael De Vlieger, Table of n, a(n) for n = 0..467

Crossrefs

Cf. A000040, A076794.

Partial sums of A034785.

Programs

Mathematica

Table[Sum[2^Prime[k], {k, n}], {n, 0, 18}] (* Michael De Vlieger, Jul 14 2017 *)

PARI

a(n) = sum(k=1, n, 2^prime(k)) \\ Michel Marcus, Jul 23 2013

Formula

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

Extensions

More terms from R. J. Mathar, Aug 31 2007