A004620 - OEIS

A004620

Divisible only by primes congruent to 2 mod 7.

1, 2, 4, 8, 16, 23, 32, 37, 46, 64, 74, 79, 92, 107, 128, 148, 149, 158, 163, 184, 191, 214, 233, 256, 296, 298, 316, 317, 326, 331, 359, 368, 373, 382, 401, 428, 443, 457, 466, 499, 512, 529, 541, 569, 592, 596

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OFFSET

1,2

LINKS

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

MATHEMATICA

ok[1]=True; ok[n_]:=And@@(Mod[#, 7]==2&)/@FactorInteger[n][[All, 1]]; Select[Range[6000], ok] (* Vincenzo Librandi, Aug 20 2012 *)

PROG

(Magma) [n: n in [1..1000] | forall{d: d in PrimeDivisors(n) | d mod 7 eq 2}]; // Vincenzo Librandi, Aug 20 2012

CROSSREFS

Sequence in context: A004207 A219675 A062729 * A018618 A294364 A108566

Adjacent sequences: A004617 A004618 A004619 * A004621 A004622 A004623

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane

EXTENSIONS

Offset changed from 0 to 1 by Vincenzo Librandi, Aug 20 2012

STATUS

approved