a(n) = pi(Mersenne(n)): index of n-th Mersenne prime.

A059305

a(n) = pi(Mersenne(n)): index of n-th Mersenne prime.

Terms

    a(0) =2a(1) =4a(2) =11a(3) =31a(4) =1028a(5) =12251a(6) =43390a(7) =105097565

External references