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A004619 Numbers divisible only by primes congruent to 1 mod 7. 2
1, 29, 43, 71, 113, 127, 197, 211, 239, 281, 337, 379, 421, 449, 463, 491, 547, 617, 631, 659, 673, 701, 743, 757, 827, 841, 883, 911, 953, 967, 1009, 1051, 1093, 1163, 1247, 1289, 1303, 1373, 1429, 1471 (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]==1&)/@FactorInteger[n][[All, 1]]; Select[Range[6000], ok] (* Vincenzo Librandi, Aug 20 2012 *)

PROG

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

(PARI) is(n)=if(n%7!=1, return(0)); my(f=factor(n)[, 1]); for(i=1, #f~, if(f[i]%7!=1, return(0))); 1 \\ Charles R Greathouse IV, Jul 02 2016

CROSSREFS

Sequence in context: A162357 A316741 A173967 * A140444 A042969 A042967

Adjacent sequences:  A004616 A004617 A004618 * A004620 A004621 A004622

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified October 16 09:02 EDT 2021. Contains 348041 sequences. (Running on oeis4.)