a(n) = Sum_{k=1..n} -mu(k+1) * a(n-k), with a(0)=1.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =6a(5) =9a(6) =17a(7) =28a(8) =50a(9) =83a(10) =147a(11) =249a(12) =435a(13) =742a(14) =1288a(15) =2207a(16) =3819a(17) =6561a(18) =11333a(19) =19497a(20) =33640a(21) =57915a(22) =99874a(23) =172020a(24) =296550a(25) =510886a(26) =880580a(27) =1517226a(28) =2614889a(29) =4505745