(n, a)
return _s11(n, a, a)
Get all permutations of [a, a, 0, 0, ..., 0] of length n.
    len(out) == (n-1)*n / 2.
Get all permutations of [a, a, 0, 0, ..., 0] of length n.
    len(out) == (n-1)*n / 2.
Get all permutations of [ a a 0 0 ... 0 ] of length n . len ( out ) == ( n - 1 ) * n / 2 .
def _s2(n, a):
    """Get all permutations of [a, a, 0, 0, ..., 0] of length n.
    len(out) == (n-1)*n / 2.
    """
    return _s11(n, a, a)
def _s2 ( n , a ) : return _s11 ( n , a , a )