A004617 Divisible only by primes congruent to 3 mod 5.

1, 3, 9, 13, 23, 27, 39, 43, 53, 69, 73, 81, 83, 103, 113, 117, 129, 159, 163, 169, 173, 193, 207, 219, 223, 233, 243, 249, 263, 283, 293, 299, 309, 313, 339, 351, 353, 373, 383, 387, 433, 443, 463, 477, 489, 503

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn

Links

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

Programs

Magma

[n: n in [1..510] | forall{d: d in PrimeDivisors(n) | d mod 5 eq 3}]; // Bruno Berselli, Aug 11 2012

Mathematica

ok[1] = True; ok[n_] := And@@ (Mod[#, 5] == 3&)/@ FactorInteger[n][[All,1]]; Select[Range[2000],ok] (* Vincenzo Librandi, Aug 11 2012 *)