Position at which 2^n occurs in A057926, or -1 if it does not occur.

Terms

a(0) =0a(1) =-1a(2) =2a(3) =3a(4) =6a(5) =9a(6) =15a(7) =27a(8) =36a(9) =51a(10) =87a(11) =135a(12) =243a(13) =315a(14) =531a(15) =735a(16) =969a(17) =1707a(18) =2679a(19) =3831a(20) =6363a(21) =9663a(22) =14559a(23) =23091a(24) =33045a(25) =45999a(26) =77523a(27) =120471a(28) =177639a(29) =252717