login
A004623
Divisible only by primes congruent to 5 mod 7.
1
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
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
KEYWORD
nonn
STATUS
approved