E.g.f. exp(x+1/6*x^3+1/24*x^4).

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =6a(5) =16a(6) =46a(7) =176a(8) =722a(9) =2906a(10) =13106a(11) =66716a(12) =345676a(13) =1849992a(14) =10802156a(15) =66543296a(16) =418075036a(17) =2750329276a(18) =19145683612a(19) =137410493656