Numbers k such that the k-th cyclotomic polynomial has a root mod 5.

Terms

a(0) =1a(1) =2a(2) =4a(3) =5a(4) =10a(5) =20a(6) =25a(7) =50a(8) =100a(9) =125a(10) =250a(11) =500a(12) =625a(13) =1250a(14) =2500a(15) =3125a(16) =6250a(17) =12500a(18) =15625a(19) =31250a(20) =62500a(21) =78125a(22) =156250a(23) =312500a(24) =390625a(25) =781250a(26) =1562500a(27) =1953125a(28) =3906250a(29) =7812500