a(n) = round(n*exp(n)).

Terms

a(0) =0a(1) =3a(2) =15a(3) =60a(4) =218a(5) =742a(6) =2421a(7) =7676a(8) =23848a(9) =72928a(10) =220265a(11) =658616a(12) =1953057a(13) =5751374a(14) =16836460a(15) =49035261a(16) =142177768a(17) =410634197a(18) =1181879444a(19) =3391163718a(20) =9703303908a(21) =27695130424a(22) =78868082615a(23) =224130479264a(24) =635738931116