{{alias}}( n )
    Computes the nth Tribonacci number.

    Tribonacci numbers follow the recurrence relation

      F_n = F_{n-1} + F_{n-2} + F_{n-3}

    with seed values F_0 = 0, F_1 = 0, and F_2 = 1.

    If `n` is greater than `63`, the function returns `NaN`, as larger
    Tribonacci numbers cannot be accurately represented due to limitations of
    double-precision floating-point format.

    If not provided a nonnegative integer value, the function returns `NaN`.

    If provided `NaN`, the function returns `NaN`.

    Parameters
    ----------
    n: integer
        Input value.

    Returns
    -------
    y: integer
        Tribonacci number.

    Examples
    --------
    > var y = {{alias}}( 0 )
    0
    > y = {{alias}}( 1 )
    0
    > y = {{alias}}( 2 )
    1
    > y = {{alias}}( 3 )
    1
    > y = {{alias}}( 4 )
    2
    > y = {{alias}}( 64 )
    NaN
    > y = {{alias}}( NaN )
    NaN

    See Also
    --------