58003domain: NAppears in sequencesa(n) is the number of numbers removed in each step of Eratosthenes's sieve for 10!.at n=5A145537Numbers k that are the products of two distinct primes such that 2*k-1, 4*k-3, 8*k-7, 16*k-15, 32*k-31 and 64*k-63 are also products of two distinct primes.at n=26A177215