Return to Revisions

I won't bet my hand for this but seems to be ok:

ClearAll[return];
return[x : {0 ..., 1}, list_] := {#, list[[;; #]]} &[Length@x];
return[x_, y_] := {Length@y, y};

sqPeriod[list_] := return[FindLinearRecurrence[list], list]



sqPeriod /@ {
   {19, 6, 19, 6, 19, 6, 19, 6, 19, 6, 19, 6},
   {73, 7, 4, 73, 7, 4, 73, 7, 4, 73, 7, 4, 73, 7},
   {73, 7, 4, 7, 2, 6, 7, 2, 7, 73, 9, 17, 7, 7}
   } // Column