Number of principal reversible magic squares of order 4n.

Terms

a(0) =1a(1) =3a(2) =10a(3) =42a(4) =35a(5) =42a(6) =230a(7) =42a(8) =126a(9) =393a(10) =230a(11) =42a(12) =1190a(13) =42a(14) =230a(15) =1158a(16) =462a(17) =42a(18) =3030a(19) =42a(20) =1190a(21) =1158a(22) =230a(23) =42a(24) =5922a(25) =393a(26) =230a(27) =3030a(28) =1190a(29) =42