Replicate pandas quarterly resample with monthly resample

Question

Is there a way to replicate df.resample('QS') using monthly resample?

For example

index = pd.date_range('1/2/2000', periods=11, freq='MS')
series = pd.Series(range(11), index=index)
series.resample('QS').sum()

Gives me

2000-01-01     1
2000-04-01     9
2000-07-01    18
2000-10-01    27

But

series.resample('3MS', origin='2000-04-01').sum()

Gives me

2000-02-01     3
2000-05-01    12
2000-08-01    21
2000-11-01    19

Expected output is

2000-01-01     1
2000-04-01     9
2000-07-01    18
2000-10-01    27