941010270domain: NAppears in sequencesa(n) = lcm(1, 2, ..., 2n) / lcm(1, 2, ..., n).at n=21A093880a(n) = product of primes p such that p^k <= n < 2*p^k for some k >= 1.at n=41A366369a(n) = product of primes p such that p^k <= n < 2*p^k for some k >= 1.at n=42A366369