Number of ways of pairing numbers 1 to n with numbers n+1 to 2n such that each pair sums to a prime.

A070897

Number of ways of pairing numbers 1 to n with numbers n+1 to 2n such that each pair sums to a prime.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =4a(6) =8a(7) =36a(8) =40a(9) =49a(10) =126a(11) =121a(12) =440a(13) =2809a(14) =11395a(15) =32761a(16) =132183a(17) =881721a(18) =3015500a(19) =19642624a(20) =106493895a(21) =249987721a(22) =1257922092a(23) =4609187881a(24) =29262161844a(25) =189192811369

External references