from pandas import DataFrame, Series, to_datetime

def signals(data: DataFrame) -> Series:
    """
    Generate long signals based on the day of the week and downward close conditions.

    Returns a Series with 'L' for long signals and 'N' for no signal.
    """
    date_series = to_datetime(data['Date'], errors = 'coerce')
    monday_or_tuesday = date_series.dt.dayofweek.isin([0, 1])
    lower_past_two_days = (data['Close'] < data['Close'].shift(1)) & (data['Close'].shift(1) < data['Close'].shift(2))

    signals = Series('N', index=data.index)
    signals[monday_or_tuesday & lower_past_two_days] = 'L'

    return signals