Number of non-equivalent ways to place 4 non-attacking kings on an n X n board.

Terms

a(0) =0a(1) =0a(2) =1a(3) =14a(4) =277a(5) =2154a(6) =10855a(7) =39926a(8) =120961a(9) =315150a(10) =737089a(11) =1577406a(12) =3150841a(13) =5934034a(14) =10651567a(15) =18332614a(16) =30452605a(17) =49011606a(18) =76753681a(19) =117268590a(20) =175315789a(21) =256949306a(22) =369978631a(23) =524114454a(24) =731604457a(25) =1007394974a(26) =1369985905a(27) =1841600286a(28) =2449309201a(29) =3225197730