a(n) = 1 + sum{p=primes<n, p does not divide n} a(p).

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =4a(5) =5a(6) =8a(7) =15a(8) =14a(9) =11a(10) =16a(11) =29a(12) =32a(13) =55a(14) =58a(15) =63a(16) =64a(17) =125a(18) =128a(19) =251a(20) =246a(21) =239a(22) =256a(23) =509a(24) =508a(25) =479a(26) =510a(27) =503a(28) =512a(29) =1017