Number of ways to place 4 points on a triangular grid of side n so that no two of them are adjacent.

A239570

Number of ways to place 4 points on a triangular grid of side n so that no two of them are adjacent.

Terms

    a(0) =0a(1) =1a(2) =114a(3) =1137a(4) =6100a(5) =23265a(6) =71211a(7) =186739a(8) =436437a(9) =932850a(10) =1856305a(11) =3483546a(12) =6224439a(13) =10668112a(14) =17640000a(15) =28271370a(16) =44083006a(17) =67084839a(18) =99893412a(19) =145869175a(20) =209275710a(21) =295463091a(22) =411077689a(23) =564300837a(24) =765118875a(25) =1025627200a(26) =1360371051a(27) =1786725864a(28) =2325320137

External references