The third left hand column of triangle A167580.

Terms

a(0) =3a(1) =98a(2) =1080a(3) =7568a(4) =40976a(5) =187488a(6) =761600a(7) =2830848a(8) =9821952a(9) =32254464a(10) =101263360a(11) =306229248a(12) =897175552a(13) =2558058496a(14) =7123894272a(15) =19434569728a(16) =52063567872a(17) =137236709376a(18) =356550967296a(19) =914355126272