task1231231231231

program Project7;

{$APPTYPE CONSOLE}
{$R *.res}

uses System.SysUtils;

function CalcTask(a, n: Integer): Double;
var
  DenominValues: array of Double;
  i: Integer;
begin
  Result := 0;
  if n <= 0 then raise Exception.Create('Косяк при вводе N');
  if a < 0 then raise Exception.Create('Косяк при вводе A');
  SetLength(DenominValues, n - 1);
  DenominValues[0] := (1 + a);

  for i := 1 to Length(DenominValues) - 1 do
  begin
    DenominValues[i] := DenominValues[i - 1] * (a + i + 1);
  end;

  for i := 0 to Length(DenominValues) - 1 do
  begin
    Result := Result + 1 / DenominValues[i];
  end;
end;

var
  a, n: Integer;

begin
  try
    Write('Введите A: ');
    ReadLn(a);
    Write('Введите N: ');
    ReadLn(n);
    WriteLn(CalcTask(a, n));
  except
    on E: Exception do WriteLn(E.ClassName, ': ', E.Message);
  end;
  Readln;

end.