OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
8 is in the sequence because the sum of the first 8 primes is 2 + 3 + 5 + 7 + 11 + 13 + 17 + 19 = 77 = 7*11, which is semiprime.
MAPLE
with(numtheory): for n from 1 to 500 do:s:=sum(‘ithprime(k)’, ’k’=1..n):if bigomega(s)=2 then printf(`%d, `, n):else fi:od:
MATHEMATICA
Flatten[Position[Accumulate[Prime[Range[300]]], _?(PrimeOmega[#]==2&)]]
PROG
(PARI) isok(n) = bigomega(vecsum(primes(n))) == 2; \\ Michel Marcus, Sep 18 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Jun 17 2012
STATUS
approved