A115606 Partial sums of A102540 (primes that are not Chen primes).

0, 43, 104, 177, 256, 353, 456, 607, 770, 943, 1136, 1359, 1588, 1829, 2100, 2377, 2660, 2973, 3304, 3653, 4020, 4393, 4776, 5173, 5594, 6027, 6466, 6923, 7386, 7909, 8456, 9049, 9650, 10257, 10870, 11489, 12132, 12793, 13466, 14157, 14866, 15593

Offset

0,2

Comments

See also A109611 (Chen primes: primes p such that p + 2 is either a prime or a semiprime), A102540 (primes that are not Chen primes). a(n) is prime for a(1) = 43, a(5) = 353 [Chen prime], a(7) = 607, a(15) = 2377, a(31) = 9049, a(35) = 11489 [Chen prime], a(49) = 22013. a(n) is semiprime for a(3) = 177, a(9) = 943, a(13) = 1829, a(17) = 2973, a(19) = 3653, a(21) = 4393, a(23) = 5173, a(24) = 5594, a(29) = 7909, a(37) = 12793, a(38) = 13466, a(40) = 14866, a(41) = 15593, a(43) = 17065, a(45) = 18595.

Links

Table of n, a(n) for n=0..41.

Formula

a(n) = SUM[k=1..n] A102540(k).

Example

a(5) = 43 + 61 + 73 + 79 + 97 = 353, which happens to be the Chen prime A109611(52).

Crossrefs

Cf. A000040, A001358, A007504, A102540, A109611.

Sequence in context: A142795 A325077 A023293 * A194773 A154506 A044230

Adjacent sequences: A115603 A115604 A115605 * A115607 A115608 A115609

Keyword

easy,nonn

Author

Jonathan Vos Post, Mar 09 2006

Status

approved