Divisors of Fermat numbers.

Terms

a(0) =1a(1) =3a(2) =5a(3) =17a(4) =257a(5) =641a(6) =65537a(7) =114689a(8) =274177a(9) =319489a(10) =974849a(11) =2424833a(12) =6700417a(13) =13631489a(14) =26017793a(15) =45592577a(16) =63766529a(17) =167772161a(18) =825753601a(19) =1214251009a(20) =4294967297a(21) =6487031809a(22) =70525124609a(23) =190274191361a(24) =311453532161a(25) =646730219521