A128402 Numbers k such that k^2 divides 22^k-1.

1, 3, 7, 21, 39, 273, 507, 3081, 3549, 21567, 40053, 78117, 280371, 343239, 546819, 1015521, 2056899, 2402673, 5998317, 6171243, 7108647, 8740173, 12338859, 14398293, 18988203, 27115881, 41988219, 43198701, 47727771, 55431363

Offset

1,2

Links

Table of n, a(n) for n=1..30.

Maple

select(t -> 22 &^ t - 1 mod t^2 = 0, [seq(2*k+1, k=0..10^6)]); # Robert Israel, Jan 23 2015

Mathematica

a={}; Do[r=(22^n-1)/n^2; If[r==IntegerPart[r], AppendTo[a, n]], {n, 1, 10^3}]; a (* Vladimir Joseph Stephan Orlovsky, Aug 07 2008 *)

Prog

(PARI) { forstep(m=11, 10^8, 2, if( Mod(22, m^2)^m==1, print(m) ) ) } \\ Max Alekseyev, Oct 18 2008

Crossrefs

Cf. A127103, A127104, A127105, A127106, A127107, A127102, A127101, A127100, A127092, A128405, A128393, A128394, A128395, A128396, A128397, A128398, A128399, A128400, A128401, A128403, A128404.

Sequence in context: A018572 A018641 A097162 * A018689 A119959 A329114

Adjacent sequences: A128399 A128400 A128401 * A128403 A128404 A128405

Keyword

nonn,less

Author

Alexander Adamchuk, Mar 01 2007

Extensions

a(14)-a(30) from Max Alekseyev, Oct 18 2008

Status

approved