program Tinh_Tong;
var
n, i, A: integer;
begin
write('Nhap n: ');
readln(n);
i := 0;
A := 0;
while i <= (2 * n + 1) do
begin
A := A + i;
i := i + 2;
end;
writeln('Tong cac so le tu 1 den 2*n+1 la: ', A);
readln;
end.
program Tinh_Tong;
var n, A, i: integer;
begin
write('Nhap vao so nguyen duong n: ');
readln(n);
A := 0;
i := 0;
while i <= n do
begin
A := A + 2 * i + 1;
i := i + 1;
end;
writeln('Tong A = 1 + 3 + 5 + ... + (2 * ', n, ' + 1) = ', A);
end.