A049045 Domain of A049044.

1, 2, 4, 5, 7, 10, 11, 14, 17, 19, 22, 23, 31, 34, 37, 38, 41, 46, 61, 62, 71, 73, 74, 77, 82, 89, 103, 113, 122, 131, 139, 142, 146, 154, 157, 163, 167, 173, 178, 191, 193, 197, 206, 211, 226, 227, 233, 239, 251, 257, 262, 263, 278, 283, 293, 307, 313, 314, 317

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Comments

Positive integers that divide some positive element of A003422.

From Robert Israel, Nov 14 2016: (Start)

Numbers n such that A013584(n) > 0.

If n is in the sequence, then so are all divisors of n. (End)

Links

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

Crossrefs

A049044, A003422, A013584.

Complement of A275608.

Programs

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 false fi;
    t:= t + r mod n;
    if t = 0 then return true fi;
  od;
end proc:
filter(1):= true:
select(filter, [$1..1000]); # Robert Israel, Nov 14 2016

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[False]]; t = Mod[t + r, n]; If[t == 0, Return[True]]]];
okQ[1] = True;
Select[Range[1000], okQ] (* Jean-François Alcover, Apr 10 2019, after Robert Israel *)