def test8_three():
actual = sum_series2(3, 2, 1)
expected = 4
assert actual == expected
def test8_ten():
actual = sum_series2(10, 2, 1)
expected = 123
assert actual == expected
def test8_one():
actual = sum_series2(1, 2, 1)
expected = 1
assert actual == expected
def test8_two():
actual = sum_series2(2, 2, 1)
expected = 3
assert actual == expected
def test8_zero():
actual = sum_series2(0, 2, 1)
expected = 2
assert actual == expected
def test7_ten():
actual = sum_series2(10)
expected = 55
assert actual == expected
def test7_three():
actual = sum_series2(3)
expected = 2
assert actual == expected
def test7_two():
actual = sum_series2(2)
expected = 1
assert actual == expected
def test7_zero():
actual = sum_series2(0)
expected = 0
assert actual == expected