Expansion of Product_{k>=1} 1/(1 - phi(k)*x^k), where phi = Euler totient function (A000010).

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =7a(5) =13a(6) =22a(7) =38a(8) =63a(9) =105a(10) =174a(11) =278a(12) =447a(13) =707a(14) =1122a(15) =1766a(16) =2729a(17) =4213a(18) =6482a(19) =9880a(20) =15069a(21) =22799a(22) =34290a(23) =51378a(24) =76777a(25) =114365a(26) =169324a(27) =250162a(28) =368505a(29) =540575