Number of nonoverlapping placements of one 1 X 1 square and one 2 X 2 square on an n X n board.

Terms

a(0) =0a(1) =0a(2) =20a(3) =108a(4) =336a(5) =800a(6) =1620a(7) =2940a(8) =4928a(9) =7776a(10) =11700a(11) =16940a(12) =23760a(13) =32448a(14) =43316a(15) =56700a(16) =72960a(17) =92480a(18) =115668a(19) =142956a(20) =174800a(21) =211680a(22) =254100a(23) =302588a(24) =357696a(25) =420000a(26) =490100a(27) =568620a(28) =656208a(29) =753536