SQL & PL/SQL

Hi,

I have to get the previous three year-month of actual date but I have a problem for the beginning of the year and this is because I define the erroneus query.

I mean:

I've written this query

SELECT TO_CHAR(SYSDATE,'YYYYMM')-1, TO_CHAR(SYSDATE,'YYYYMM')-2, TO_CHAR(SYSDATE,'YYYYMM')-3

FROM DUAL;

in order to get (on March):

201502, 201501, 201412

but unfortunately I get:

201502, 201501, 201500

Can you help me?

Thanks in advance!