Only Fermat number divisible by A023394(n) is 2^2^a(n) + 1.

Terms

a(0) =0a(1) =1a(2) =2a(3) =3a(4) =5a(5) =4a(6) =12a(7) =6a(8) =11a(9) =11a(10) =9a(11) =5a(12) =18a(13) =12a(14) =10a(15) =12a(16) =23a(17) =16a(18) =15a(19) =10a(20) =19a(21) =12a(22) =19a(23) =13a(24) =36a(25) =21a(26) =38a(27) =32a(28) =25a(29) =17