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

Terms

a(0) =0a(1) =0a(2) =2a(3) =6a(4) =17a(5) =47a(6) =128a(7) =349a(8) =948a(9) =2579a(10) =7011a(11) =19058a(12) =51806a(13) =140824a(14) =382800a(15) =1040560a(16) =2828536a(17) =7688760a(18) =20900217a(19) =56812680a(20) =154432878a(21) =419792086a(22) =1141113200a(23) =3101867275a(24) =8431749450a(25) =22919871312a(26) =62302669700a(27) =169356214910a(28) =460357921527