Positive integers m with m^k - 1 (k = 1,...,13) all practical.

Terms

a(0) =169a(1) =625a(2) =729a(3) =1089a(4) =1681a(5) =3969a(6) =4225a(7) =5929a(8) =6241a(9) =6561a(10) =6889a(11) =8647a(12) =9409a(13) =11449a(14) =14641a(15) =15625a(16) =16129a(17) =18769a(18) =20449a(19) =22201a(20) =24649a(21) =27561a(22) =28561a(23) =30625a(24) =32761a(25) =33331a(26) =33489a(27) =33661a(28) =34969a(29) =35209