Faute d'un programme pascal

  
program app;
uses wincrt;
var
a,b: longint; m,n,i,j,x,l: integer; f: text; w,r:boolean; ch,ch1: string;
procedure remplire (var a,b: longint);
begin
repeat
writeln ('saisir B: '); readln(b);
until ((b>2) and (b<50000));
repeat
writeln ('saisir A: '); readln(a);
until (a<b);
end;
function puissance (x:integer): integer;
begin
l:=1;
for i:=1 to x do
l:=l*2;
puissance:=l;
end; 
function premier (j: integer): boolean;
begin
w:=true;
for i:=2 to j div 2 do
begin
if j mod i = 0 then w:= false;
end;
premier := w;
end;
procedure verif (m:longint; var n: integer; var r: boolean);
begin
n:=0; r:=false;
for j:=3 to m do
begin
if (premier(j)) and (puissance(j)= m+1) then begin n:=j; r:=true; end;
end;
end;
procedure calcul (a,b: longint; var f: text);
begin
rewrite(f);
r:=false;
for i:= a to b do
begin
verif(i,n,r);
if r then begin str(n,ch); str(i,ch1);
          writeln(f,ch1+'='+'(2^'+ch+')-1');
          end;
end;
close(f);
end;
procedure affiche (var f:text);
begin
reset(f);
while not eof(f) do
begin
readln(f,ch);
writeln (ch);
end;
close(f);
end;
begin
assign(f,'c:/omar.txt');
remplire(a,b);
calcul(a,b,f);
affiche(f);
end.