a(n) = pi((sqrt(P(n))+1)^2) - pi(P(n)), where pi(n) = number of primes <= n and P(n) = n-th primorial.
A166678
a(n) = pi((sqrt(P(n))+1)^2) - pi(P(n)), where pi(n) = number of primes <= n and P(n) = n-th primorial.
Terms
- a(0) =2a(1) =2a(2) =3a(3) =6a(4) =14a(5) =34a(6) =110a(7) =384a(8) =1540a(9) =7019a(10) =34501a(11) =183439a(12) =1045196a(13) =6164423a(14) =38285946
External references
- oeis: A166678