Number of non-degenerate parallelograms in an n X n permutation array.

Terms

a(0) =0a(1) =0a(2) =0a(3) =6a(4) =62a(5) =362a(6) =1266a(7) =3692a(8) =8904a(9) =19376a(10) =38144a(11) =70574a(12) =122478a(13) =203722a(14) =324554a(15) =500868a(16) =749128a(17) =1094204a(18) =1560240a(19) =2183562a(20) =2998598a(21) =4055502a(22) =5402450a(23) =7107528a(24) =9233488a(25) =11870016a(26) =15100040a(27) =19037586a(28) =23787678a(29) =29495558