Maximal values of permanent on (0,1) square matrices of order n with row and column sums 3.

Terms

a(0) =6a(1) =9a(2) =13a(3) =36a(4) =54a(5) =81a(6) =216a(7) =324a(8) =486a(9) =1296a(10) =1944a(11) =2916a(12) =7776a(13) =11664a(14) =17496a(15) =46656a(16) =69984a(17) =104976a(18) =279936a(19) =419904a(20) =629856a(21) =1679616a(22) =2519424a(23) =3779136a(24) =10077696a(25) =15116544a(26) =22674816a(27) =60466176a(28) =90699264a(29) =136048896