program numeric;

{$APPTYPE CONSOLE}

uses
  SysUtils;

var c:array[1..45] of integer;
n:integer;
k:int64;
procedure p(i,v:integer);
var j:integer;
begin
c[i]:=v;
if i=n then begin
//for i:=1 to n do write(c[i]);writeln;
k:=k+1;
end
else
begin
if (c[i]<>1) and (c[i]<>2) then p(i+1,1);
if (c[i]=1)and(i<n-1) then p(i+1,2);
if (c[i]=2)and(i<n-1) then p(i+1,2);
if c[i]=1 then p(i+1,3);
if c[i]=2 then p(i+1,3);

end;

end;

begin
//readln(n);


for n:=1 to 20 do
begin
k:=0;
p(1,1);
p(1,3);
writeln(k);
end;
readln;
end.