A161626 Sum of all numbers from 2*n-1 up to prime(n).

3, 3, 5, 7, 30, 36, 75, 85, 140, 264, 286, 450, 561, 595, 722, 966, 1242, 1296, 1612, 1815, 1881, 2257, 2496, 2924, 3577, 3876, 3978, 4293, 4399, 4730, 6298, 6693, 7373, 7519, 8829, 8991, 9775, 10591, 11102, 11970, 12870, 13068, 14766, 14980, 15587, 15805

Offset: 1

Author

Juri-Stepan Gerasimov, Jun 15 2009

Keywords

• nonn
• easy

Examples

			a(1) = 1+2 = 3;
a(2) = 3;
a(3) = 5;
a(5) = 9+10+11 = 30.
		

Crossrefs

Cf. A000027, A000040, A161570.

Programs

Maple

A000217 := proc(n) n*(n+1) /2 ; end:
A161626 := proc(n) A000217(ithprime(n))-A000217(2*n-2) ; end: seq(A161626(n),n=1..120) ; # R. J. Mathar, Oct 02 2009

Formula

a(n) = A000217(A000040(n)) - A000217(2*n-2).

Extensions

Edited and corrected by R. J. Mathar, Oct 02 2009

Inserted a zero in an A-number - R. J. Mathar, Oct 23 2009