A208155 7-Knödel numbers.

15, 49, 91, 133, 217, 259, 301, 427, 469, 511, 553, 679, 721, 763, 889, 973, 1015, 1057, 1099, 1141, 1267, 1351, 1393, 1477, 1561, 1603, 1687, 1897, 1939, 1981, 2107, 2149, 2191, 2317, 2359, 2443, 2569, 2611, 2653, 2779, 2863, 2947, 3031, 3073, 3199, 3241, 3409

Offset: 1

Author

Paolo P. Lava, Feb 24 2012

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000
• Eric Weisstein, Knödel Numbers.

Crossrefs

Cf. A002997, A050990, A033553, A050992, A050993, A208154, A208156-A208158.

Programs

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(10000,7);

Mathematica

(* First run program for A208154 to define knodelQ *) Select[Range[3500], knodelQ[#, 7] &] (* Alonso del Arte, Feb 24 2012 *)