A004623 Divisible only by primes congruent to 5 mod 7.

1, 5, 19, 25, 47, 61, 89, 95, 103, 125, 131, 173, 229, 235, 257, 271, 305, 313, 361, 383, 397, 439, 445, 467, 475, 509, 515, 523, 593, 607, 625, 655, 677, 691, 719, 733, 761, 859, 865, 887, 893, 929, 971, 1013

Offset

1,2

Links

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

Mathematica

 ok[1]=True; ok[n_]:=And@@(Mod[#, 7]==5&)/@FactorInteger[n][[All, 1]]; Select[Range[5000], ok] (* Vincenzo Librandi, Aug 20 2012 *)

Prog

(Magma) [n: n in [1..2000] | forall{d: d in PrimeDivisors(n) | d mod 7 eq 5}]; // Vincenzo Librandi, Aug 20 2012

Crossrefs

Sequence in context: A106957 A236167 A022143 * A018475 A119238 A218885

Adjacent sequences: A004620 A004621 A004622 * A004624 A004625 A004626

Keyword

nonn

Author

N. J. A. Sloane

Status

approved