Number of ways to place 7 nonattacking kings on a 7 X n board.

Terms

a(0) =0a(1) =0a(2) =24a(3) =926a(4) =37282a(5) =394202a(6) =2484382a(7) =10999618a(8) =38168864a(9) =110899878a(10) =281638602a(11) =643766432a(12) =1352358921a(13) =2651129458a(14) =4906381466a(15) =8648792662a(16) =14623854922a(17) =23851793294a(18) =37697787702a(19) =57953320884a(20) =86929476107a(21) =127563008202a(22) =183536011462a(23) =259410007946a(24) =360775279732