a(n) = floor(e^n / n^e).

Terms

a(0) =2a(1) =1a(2) =1a(3) =1a(4) =1a(5) =3a(6) =5a(7) =10a(8) =20a(9) =42a(10) =88a(11) =189a(12) =414a(13) =921a(14) =2077a(15) =4737a(16) =10921a(17) =25416a(18) =59646a(19) =141033a(20) =335752a(21) =804258a(22) =1937372a(23) =4690989a(24) =11412140a(25) =27884328a(26) =68407056a(27) =168446547a(28) =416226830a(29) =1031816793