1666666666domain: NAppears in sequencesa(n) = floor(10^10/n).at n=5A057072Numbers n such that (n+n+1) divides the decimal concatenation [n, n+1].at n=18A173712Number of composites removed in each step of the Sieve of Eratosthenes for 10^10.at n=1A227799a(n) = (5*10^n - 2)/3.at n=9A246057