Number of ways to place 3 nonattacking kings on a 3 X n board.

Terms

a(0) =0a(1) =0a(2) =8a(3) =34a(4) =105a(5) =248a(6) =490a(7) =858a(8) =1379a(9) =2080a(10) =2988a(11) =4130a(12) =5533a(13) =7224a(14) =9230a(15) =11578a(16) =14295a(17) =17408a(18) =20944a(19) =24930a(20) =29393a(21) =34360a(22) =39858a(23) =45914a(24) =52555a(25) =59808a(26) =67700a(27) =76258a(28) =85509a(29) =95480