OFFSET
1,1
COMMENTS
Prime subsequence begins: 13,31,61,73,97,113,139,151,163,179,193.
Semiprime subsequence begins: 21,39,55,87,119,209,215,253,287,301,323.
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
FORMULA
a(n) ~ 2n log n. - Charles R Greathouse IV, Feb 23 2017
MATHEMATICA
Module[{od=Select[Range[1, 401, 2], PrimeOmega[#]==2&], ev=Select[ Range[ 2, 402, 2], PrimeOmega[#] ==2&], len}, len=Min[Length[od], Length[ev]]; Total/@ Thread[{Take[od, len], Take[ev, len]}]] (* Harvey P. Dale, Jun 07 2018 *)
PROG
(PARI) list(lim)=my(P=2*primes([2, lim\2]), v=List()); forprime(p=3, lim\3, forprime(q=3, min(lim\p, p), listput(v, p*q))); v=Set(v); for(i=1, min(#P, #v), P[i]+=v[i]); P=P[1..min(#P, #v)]; select(k->k<=lim, P) \\ Charles R Greathouse IV, Feb 23 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Zak Seidov, Feb 22 2017
STATUS
approved