a(n) = round(e^(n+1)/(e^2+1)).

Terms

a(0) =0a(1) =1a(2) =2a(3) =7a(4) =18a(5) =48a(6) =131a(7) =355a(8) =966a(9) =2626a(10) =7137a(11) =19401a(12) =52737a(13) =143354a(14) =389676a(15) =1059250a(16) =2879341a(17) =7826860a(18) =21275612a(19) =57833109a(20) =157206689a(21) =427332086a(22) =1161609045a(23) =3157580760a(24) =8583194401a(25) =23331541370a(26) =63421704936a(27) =172398068059a(28) =468626535665