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
Keywords
Examples
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.
Links
- Robert Israel, Table of n, a(n) for n = 1..10000
Programs
-
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 &] -
PARI
s = 0; forprime(p=3, 1e4, s += p; if (bigomega(s)==2, print1(s, ", ")))
Comments