a(n) = ceiling(log(n)*exp(n)).

Terms

a(0) =0a(1) =6a(2) =23a(3) =76a(4) =239a(5) =723a(6) =2134a(7) =6199a(8) =17805a(9) =50718a(10) =143572a(11) =404431a(12) =1134768a(13) =3173742a(14) =8852664a(15) =24637530a(16) =68436135a(17) =189781721a(18) =525530245a(19) =1453425034a(20) =4015164095a(21) =11081117799a(22) =30554774842a(23) =84183856048a(24) =231774829750a(25) =637705962869