A004618 Divisible only by primes congruent to 4 mod 5.

1, 19, 29, 59, 79, 89, 109, 139, 149, 179, 199, 229, 239, 269, 349, 359, 361, 379, 389, 409, 419, 439, 449, 479, 499, 509, 551, 569, 599, 619, 659, 709, 719, 739, 769, 809, 829, 839, 841, 859, 919, 929, 1009, 1019

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Programs

Magma

[n: n in [1..1100] | forall{d: d in PrimeDivisors(n) | d mod 5 eq 4}]; // Vincenzo Librandi, Aug 20 2012

Mathematica

ok[1]=True;ok[n_]:=And@@(Mod[#,5]==4&)/@FactorInteger[n][[All,1]];Select[Range[4000],ok] (* Vincenzo Librandi, Aug 20 2012 *)