Number of ways to arrange 5 nonattacking triangular rooks on an n X n X n triangular grid.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =6a(7) =270a(8) =3195a(9) =21273a(10) =101484a(11) =386052a(12) =1243899a(13) =3527469a(14) =9035376a(15) =21297492a(16) =46838142a(17) =97131762a(18) =191517192a(19) =361427508a(20) =656353494a(21) =1152094086a(22) =1961910990a(23) =3251400894a(24) =5257953789a(25) =8315944731a(26) =12888836064a(27) =19609755396