OFFSET
1,1
FORMULA
a(n) = primepi(A104876(n)).
PROG
(PARI) isok(k) = bigomega(-1 + prod(j=1, k, prime(j))) == 2;
CROSSREFS
KEYWORD
more,hard,nonn
AUTHOR
Sean A. Irvine, Oct 21 2023
STATUS
approved