Bessel polynomial y_n(-1).

Terms

a(0) =1a(1) =0a(2) =1a(3) =-5a(4) =36a(5) =-329a(6) =3655a(7) =-47844a(8) =721315a(9) =-12310199a(10) =234615096a(11) =-4939227215a(12) =113836841041