Expansion of e.g.f. (1/4)*(exp(x)-x-1)*(exp(x)-1)^2.

Terms

a(0) =3a(1) =20a(2) =90a(3) =343a(4) =1197a(5) =3966a(6) =12720a(7) =39941a(8) =123651a(9) =379132a(10) =1154790a(11) =3501219a(12) =10581465a(13) =31908218a(14) =96068700a(15) =288926977a(16) =868288239a(17) =2608010424a(18) =7830584850a(19) =23505386015a(20) =70544469573a(21) =211692128950a(22) =635198021640