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

Terms

a(0) =0a(1) =0a(2) =1a(3) =4a(4) =21a(5) =115a(6) =750a(7) =5628a(8) =47811a(9) =453999a(10) =4765190a(11) =54782414a(12) =684597510a(13) =9239952802a(14) =133952757201