Number of ways to color vertices of a hexagon using <= n colors, allowing only rotations.

Terms

a(0) =0a(1) =1a(2) =14a(3) =130a(4) =700a(5) =2635a(6) =7826a(7) =19684a(8) =43800a(9) =88725a(10) =166870a(11) =295526a(12) =498004a(13) =804895a(14) =1255450a(15) =1899080a(16) =2796976a(17) =4023849a(18) =5669790a(19) =7842250a(20) =10668140a(21) =14296051a(22) =18898594a(23) =24674860a(24) =31853000a(25) =40692925a(26) =51489126a(27) =64573614