var
   i, n: integer;
   pr_item, sum: longint;
begin
     writeln('Enter num of progression elements (>=2):');
     readln(n);

     pr_item := 2;
     sum := 0;
     writeln('Summed progression elements:');
     for i := 0 to n do
     begin
          pr_item := pr_item shl 2;
          if (not odd(i)) then
          begin
             sum := sum + pr_item;
             write(pr_item, ' ');
          end;
     end;
     writeln;
     writeln('sum = ', sum);
end.

Enter num of progression elements (>=2):
10
Summed progression elements:
8 128 2048 32768 524288 8388608
sum = 8947848

var
   x, a, n, result: integer;
function f(var x:integer; var a:integer; n:integer):integer;
begin
     if (n = 1) then
        f := sqr(x+a)+a
     else
        f := sqr(f(x, a, n - 1)) + a;
end;
begin
     writeln('Enter x, a and n:');
     readln(x, a, n);
     writeln('Result = ', f(x, a, n));
end.

Enter x, a and n:
1 1 3
Result = 677