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A208158 10-Knödel numbers.

%I A208158 #20 Feb 16 2025 08:33:16
%S A208158 12,24,28,30,50,70,110,130,150,170,190,230,290,310,330,370,410,430,
%T A208158 442,470,530,532,550,590,610,670,710,730,790,830,890,910,970,1010,
%U A208158 1030,1070,1090,1130,1270,1310,1370,1390,1490,1510,1570,1630,1650,1670,1730,1790
%N A208158 10-Knödel numbers.
%H A208158 Amiram Eldar, <a href="/A208158/b208158.txt">Table of n, a(n) for n = 1..10000</a>
%H A208158 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/KnoedelNumbers.html">Knödel Numbers</a>
%p A208158 with(numtheory);
%p A208158 knodel:=proc(i,k)
%p A208158 local a,n,ok;
%p A208158 for n from k+1 to i do
%p A208158   ok:=1;
%p A208158   for a from 1 to n do
%p A208158      if gcd(a,n)=1 then  if (a^(n-k) mod n)<>1 then ok:=0; break; fi; fi;
%p A208158   od;
%p A208158   if ok=1 then print(n); fi;
%p A208158 od;
%p A208158 end:
%p A208158 knodel(10000,10)
%t A208158 Select[Range[12, 1790, 2], Divisible[# - 10, CarmichaelLambda[#]]&] (* _Jean-François Alcover_, Mar 01 2018 *)
%Y A208158 Cf. A002997, A050990, A033553, A050992, A050993, A208154-A208157.
%K A208158 nonn
%O A208158 1,1
%A A208158 _Paolo P. Lava_, Feb 24 2012