Expansion of Product_{k>=1} (1 - x^phi(k)), where phi is Euler's totient function.

Terms

a(0) =1a(1) =-2a(2) =-2a(3) =6a(4) =-4a(5) =2a(6) =6a(7) =-14a(8) =8a(9) =-2a(10) =4a(11) =-6a(12) =-16a(13) =38a(14) =-22a(15) =6a(16) =2a(17) =-10a(18) =2a(19) =6a(20) =60a(21) =-126a(22) =28a(23) =70a(24) =-38a(25) =6a(26) =-38a(27) =70a(28) =-54a(29) =38