Principal number of K. Saito for tree of type E_n.

Terms

a(0) =-1a(1) =3a(2) =0a(3) =3a(4) =5a(5) =18a(6) =66a(7) =298a(8) =1511a(9) =8670a(10) =55168a(11) =386394a(12) =2951673a(13) =24428654a(14) =217723390a(15) =2079109386a(16) =21177620171a(17) =229195610430