a(n) = [ e*a(n-1) ], where a(0) = 1.

Terms

a(0) =1a(1) =2a(2) =5a(3) =13a(4) =35a(5) =95a(6) =258a(7) =701a(8) =1905a(9) =5178a(10) =14075a(11) =38259a(12) =103998a(13) =282695a(14) =768444a(15) =2088847a(16) =5678074a(17) =15434605a(18) =41955606a(19) =114047161a(20) =310012325a(21) =842700869a(22) =2290698459a(23) =6226763995a(24) =16926099417a(25) =46009908471a(26) =125067898125a(27) =339969794796a(28) =924133715418