A248874 Primitive prime factors of the cyclotomic polynomial sequence Phi(10,k) in the order in which they occur.

11, 61, 5, 41, 521, 101, 191, 331, 1181, 9091, 13421, 19141, 2411, 71, 31, 1531, 61681, 9041, 2251, 152381, 185641, 224071, 211, 5791, 9161, 431, 1021, 271, 53951, 401, 71261, 21821, 251, 4051, 1151041, 259631, 132631, 241, 6781, 1824841, 2031671, 41011

Offset: 1

Author

Robert Price, Mar 14 2015

Keywords

• nonn

Comments

Phi(10,k) = k^4 - k^3 + k^2 - k + 1.

Note that except for a(3), all terms end with the digit 1.

Links

• Robert Price, Table of n, a(n) for n = 1..1218

Crossrefs

Cf. A005529.

Programs

Mathematica

prim = {}; Do[prim = Join[prim, Complement[First /@ FactorInteger[Cyclotomic[10, k]], prim]], {k, 1000}]; prim