Hi,
In Japan, memorials are held every 7 days from death until the
49th day, and on the following occassions: the 100th day,
1st Year, 3rd Year, 7th Year, 13th Year, 23rd Year, (25th Year),
27th Year, 33rd Year and 50th Year, and sometimes, every 50
years after the 50th year. Most sects teach that it is the
opportunity to dedicate merits to the deceased, but in
the tradition i'm in, it is another opportunity to hear the
Buddha-Dharma.
Gassho