52540domain: NAppears in sequencesNumbers k such that 5*2^k - 1 is prime.at n=34A001770Number of standard Young tableaux with n cells and 9 as last value in the first row.at n=4A245007Numbers k such that (k*2^d - 1)*(d*2^k - 1) is semiprime for some divisor d of k.at n=52A382646