a(n) = Sum_{k >= 0} floor(n^(2*k+1) / (2*k+1)!).

Terms

a(0) =0a(1) =1a(2) =3a(3) =9a(4) =25a(5) =72a(6) =199a(7) =545a(8) =1487a(9) =4048a(10) =11007a(11) =29930a(12) =81371a(13) =221199a(14) =601295a(15) =1634499a(16) =4443044a(17) =12077466a(18) =32829974a(19) =89241138a(20) =242582585a(21) =659407853a(22) =1792456409a(23) =4872401708a(24) =13244561050a(25) =36002449653a(26) =97864804699a(27) =266024120286a(28) =723128532126