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 A004621 Divisible only by primes congruent to 3 mod 7. 1
 1, 3, 9, 17, 27, 31, 51, 59, 73, 81, 93, 101, 153, 157, 177, 199, 219, 227, 241, 243, 269, 279, 283, 289, 303, 311, 353, 367, 409, 459, 471, 479, 521, 527, 531, 563, 577, 597, 619, 647, 657, 661, 681, 723, 729, 773, 787, 807, 829, 837, 849, 857, 867, 909, 933 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 MATHEMATICA ok[1]=True; ok[n_]:=And@@(Mod[#, 7]==3&)/@FactorInteger[n][[All, 1]]; Select[Range[3000], ok] (* Vincenzo Librandi, Aug 20 2012 *) PROG (MAGMA) [n: n in [1..1000] | forall{d: d in PrimeDivisors(n) | d mod 7 eq 3}]; // Vincenzo Librandi, Aug 20 2012 CROSSREFS Sequence in context: A050797 A103967 A032400 * A014209 A202253 A057258 Adjacent sequences:  A004618 A004619 A004620 * A004622 A004623 A004624 KEYWORD nonn AUTHOR EXTENSIONS Offset changed from 0 to 1 by Vincenzo Librandi, Aug 20 2012 STATUS approved

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