2718150domain: NAppears in sequencesNumber of ways of pairing odd numbers in the range 1 to n with even numbers in the range n+1 to 2n such that each pair sums to a prime.at n=27A071058Number of ways of pairing even numbers in the range 1 to n with odd numbers in the range n+1 to 2n such that each pair sums to a prime.at n=27A071059