OFFSET
1,1
COMMENTS
a(n) = A007504(k(n)), values of k(n) = 3, 7, 8, 10, 16, 18, 22, 28, 32, 34, 36, 38, 44, 46, 48, 54, 55, 58, 59, 65, 66, 72, 75, 82, 92, 93, 94, 104, 106, 110, 118, 120, 133, 136, 137, 138, 140, 141, 142, 144, 148, 150, 154, 156, 164, 168, 170, 174, 190, 194, 202, 210, 212, 218, 224, 226, 232, 234, 236, 244, 246, 249, 250, 256, 264, 272, 276, 277, 286, 294, 298, 300.
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
MAPLE
PS:= ListTools:-PartialSums(select(isprime, [2, seq(i, i=3..10^4, 2)])):
select(numtheory:-bigomega = 2, PS); # Robert Israel, Jun 23 2017
MATHEMATICA
semiPrimeQ[n_Integer] := Total[FactorInteger[n]][[2]] == 2; Select[Accumulate[Prime[Range[100]]], semiPrimeQ] (* T. D. Noe, Apr 20 2011 *)
With[{nn=200}, Select[Accumulate[Prime[Range[nn]]], PrimeOmega[#]==2&]] (* Harvey P. Dale, Dec 22 2018 *)
PROG
(PARI) {a=0; s=[]; forprime(p=2, 10^4, 2==bigomega(a=a+p)&s=concat(s, a)); s}
CROSSREFS
KEYWORD
nonn
AUTHOR
Zak Seidov, Apr 16 2011
STATUS
approved