E.g.f.: Product_{k>=1} (1 + exp(x) * x^k / k!).

Terms

a(0) =1a(1) =1a(2) =3a(3) =10a(4) =43a(5) =206a(6) =1044a(7) =5909a(8) =38371a(9) =272314a(10) =1995208a(11) =14869889a(12) =115433344a(13) =965259881a(14) =8773348601a(15) =84608514095a(16) =837220780691