Maximal length of rook tour on an n X n+4 board.

Terms

a(0) =12a(1) =36a(2) =74a(3) =134a(4) =216a(5) =328a(6) =470a(7) =650a(8) =868a(9) =1132a(10) =1442a(11) =1806a(12) =2224a(13) =2704a(14) =3246a(15) =3858a(16) =4540a(17) =5300a(18) =6138a(19) =7062a(20) =8072a(21) =9176a(22) =10374a(23) =11674a(24) =13076a(25) =14588a(26) =16210a(27) =17950a(28) =19808a(29) =21792