a(n) = ceiling(n*exp(-tan(n))).

Terms

a(0) =1a(1) =18a(2) =4a(3) =2a(4) =147a(5) =9a(6) =3a(7) =7181a(8) =15a(9) =6a(11) =23a(12) =9a(13) =1a(14) =36a(15) =12a(16) =1a(17) =57a(18) =17a(19) =3a(20) =97a(21) =22a(22) =5a(23) =203a(24) =29a(25) =8