Denominators of worst case for Engel expansion.

Terms

a(0) =1a(1) =3a(2) =5a(3) =7a(4) =7a(5) =13a(6) =19a(7) =23a(8) =31a(9) =47a(10) =61a(11) =71a(12) =73a(13) =121a(14) =121a(15) =121a(16) =121a(17) =121a(18) =121a(19) =242a(20) =484a(21) =661a(22) =661a(23) =661a(24) =1093a(25) =1753a(26) =1807a(27) =3053a(28) =3613a(29) =3613