a(n) = floor(exp(n)/n).

Terms

a(0) =2a(1) =3a(2) =6a(3) =13a(4) =29a(5) =67a(6) =156a(7) =372a(8) =900a(9) =2202a(10) =5443a(11) =13562a(12) =34031a(13) =85900a(14) =217934a(15) =555381a(16) =1420879a(17) =3647776a(18) =9393805a(19) =24258259a(20) =62800749a(21) =162950583a(22) =423687106a(23) =1103713422a(24) =2880195973a(25) =7528061901a(26) =19705490392a(27) =51652038010a(28) =135563251625