Cototient of 2^n - 1.

Terms

a(0) =0a(1) =1a(2) =1a(3) =7a(4) =1a(5) =27a(6) =1a(7) =127a(8) =79a(9) =423a(10) =111a(11) =2367a(12) =1a(13) =5799a(14) =5767a(15) =32767a(16) =1a(17) =122175a(18) =1a(19) =568575a(20) =319039a(21) =1553599a(22) =178527a(23) =10141695a(24) =1154431a(25) =22391463a(26) =20750335a(27) =135669759a(28) =3044479a(29) =539141823