A274182 Semiprimes that are the sum of the first n odd primes for some n.

15, 26, 39, 158, 326, 566, 789, 961, 1159, 1262, 1369, 1478, 1591, 1718, 1849, 2582, 3085, 3829, 4659, 5587, 7697, 8891, 10189, 13885, 14695, 16838, 17281, 18187, 19111, 20057, 22546, 24131, 25798, 26938, 27515, 28102, 35566, 36886, 38919, 41739, 43199, 50885

Offset

1,1

Comments

The set of semiprimes in A071148.

Intersection of A001358 and A071148.

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

26 appears in the sequence because 26 = 2*13 that is semiprime. Also, 3+5+7+11 = 26.
158 appears in the sequence because 158 = 2*79 that is semiprime. Also, 3+5+7+11+13+17+19+23+29+31 = 158.

Maple

P:= select(isprime, [seq(i, i=3..10^4, 2)]):
select(t -> numtheory:-bigomega(t)=2, ListTools:-PartialSums(P)); # Robert Israel, Sep 23 2019

Mathematica

Select[a = 0; Table[a = a + Prime[k], {k, 2, 300}], PrimeOmega[#] == 2 &]

Prog

(PARI) s = 0; forprime(p=3, 1e4, s += p; if (bigomega(s)==2, print1(s, ", ")))

Crossrefs

Cf. A001358, A071148, A189072, A274120.

Sequence in context: A050700 A373731 A263108 * A139566 A097963 A063936

Adjacent sequences: A274179 A274180 A274181 * A274183 A274184 A274185

Keyword

nonn

Author

K. D. Bajpai, Jun 12 2016

Status

approved