a(n) = Sum_{k=0..floor(n/5)} |Stirling1(n - 4*k,n - 5*k)|.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =1a(6) =2a(7) =4a(8) =7a(9) =11a(10) =16a(11) =24a(12) =40a(13) =72a(14) =131a(15) =231a(16) =395a(17) =675a(18) =1187a(19) =2161a(20) =4006a(21) =7414a(22) =13609a(23) =24951a(24) =46210a(25) =86930a(26) =165528a(27) =316682a(28) =606047a(29) =1161343