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A050990 2-Knödel numbers. 13
4, 6, 8, 10, 12, 14, 22, 24, 26, 30, 34, 38, 46, 56, 58, 62, 74, 82, 86, 94, 106, 118, 122, 132, 134, 142, 146, 158, 166, 178, 182, 194, 202, 206, 214, 218, 226, 254, 262, 274, 278, 298, 302, 314, 326, 334, 346, 358, 362, 382, 386, 394, 398, 422, 446, 454, 458 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers k > 2 such that A002322(k) divides k-2. Contains all doubled primes and all doubled Carmichael numbers. - Thomas Ordowski, Apr 23 2017

LINKS

R. J. Mathar, Table of n, a(n) for n = 1..690

Eric Weisstein's World of Mathematics, Knödel Numbers.

MAPLE

with(numtheory);

knodel:=proc(i, k)

local a, n, ok;

for n from k+1 to i do

  ok:=1;

  for a from 1 to n do

     if gcd(a, n)=1 then  if (a^(n-k) mod n)<>1 then ok:=0; break; fi; fi;

  od;

  if ok=1 then print(n); fi;

od;

end:

knodel(1000, 2) # Paolo P. Lava, Feb 24 2012

MATHEMATICA

Select[Range[4, 460, 2], Divisible[# - 2, CarmichaelLambda@ #] &] (* Michael De Vlieger, Apr 24 2017 *)

CROSSREFS

Cf. A002997, A033553, A050992, A050993, A208154, A208155, A208156, A208157, A208158.

Sequence in context: A061344 A066664 A064938 * A225514 A161546 A231571

Adjacent sequences:  A050987 A050988 A050989 * A050991 A050992 A050993

KEYWORD

nonn

AUTHOR

Eric W. Weisstein

STATUS

approved

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Last modified June 23 09:21 EDT 2017. Contains 288660 sequences.