A275608 Numbers that divide no nonzero terms of A003422.

3, 6, 8, 9, 12, 13, 15, 16, 18, 20, 21, 24, 25, 26, 27, 28, 29, 30, 32, 33, 35, 36, 39, 40, 42, 43, 44, 45, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 63, 64, 65, 66, 67, 68, 69, 70, 72, 75, 76, 78, 79, 80, 81, 83, 84, 85, 86, 87, 88, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100

Offset

1,1

Comments

Numbers k such that A013584(k) = 0.

If k is in the sequence, then so is every multiple of k.

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

3 is in the sequence because A003422(1)=1 and A003422(2)=2 are not divisible by 3, and A003422(k) == 1 (mod 3) for k >= 3.
4 is not in the sequence because A003422(3) = 4 is divisible by 4.

Maple

filter:= proc(n) local t, r, m;
  r:= 1; t:= 1;
  for m from 1 do
    r:= r*m mod n;
    if r = 0 then return true fi;
    t:= t + r mod n;
    if t = 0 then return false fi;
  od;
end proc:
select(filter, [$2..100]);

Mathematica

okQ[n_] := Module[{t, r, m}, r = 1; t = 1; For[m = 1, True, m++, r = Mod[r*m, n]; If[r == 0, Return[True]]; t = Mod[t + r, n]; If[t == 0, Return[False]]]];
Select[Range[2, 100], okQ] (* Jean-François Alcover, Apr 12 2019, after Robert Israel *)

Crossrefs

Cf. A003422, A013584.

Complement of A049045.

Sequence in context: A167195 A032489 A153769 * A363758 A155723 A095277

Adjacent sequences: A275605 A275606 A275607 * A275609 A275610 A275611

Keyword

nonn

Author

Robert Israel, Nov 14 2016

Status

approved