1,2

The Pari script is good up to n=9. The last 3 terms were computed by the gcc 4.1.2 program in the link. A good approximation for the n-th term is R(10^n+10^(n-1))-R(10^n) where R(x) is Riemann's approximation of the number of prime numbers < x. This is included in the Pari script. for example, Rpr11(12) = 3612792548.5108.., accurate for the first 6 digits.

Cino Hilliard, Count primes in a range.

For n=2, the 4 primes in the range 100 to 110 are 101,103,107,109. So 4 is the second entry in the sequence.

(PARI) /*Some functions*/ pr11(n) = primepi(10^n+10^(n-1))-primepi(10^n) Rpr11(n) = R(10^n+10^(n-1))-R(10^(n)) R(x) = local(j); (sum(j=1, 400, moebius(j)*Li(x^(1/j))/j)) /*End functions*/ for(x=1, 9, print1(pr11(x), ", "))

Sequence in context: A094637 A136793 A009630 this_sequence A071554 A087335 A094356

Adjacent sequences: A131040 A131041 A131042 this_sequence A131044 A131045 A131046

nonn

Cino Hilliard (hillcino368(AT)hotmail.com), Sep 23 2007