13th anniversary memorial?

If a friend died in November 2004, when would 13th anniversary memorial take place?

If a friend died in November 2004, when would 13th anniversary memorial take place?

Since you are talking about the 13th anniversary memorial, I think it concerns Buddhism.
In Buddhism, in Japan, the first anniversary of death takes place after 1 year, BUT, the other memorials take place according to the same system of the traditional age reckoning, i.d. the memorial years fall on the year of the number minus one. So, your friend’s 13th anniversary memorial takes place in 2016.

Thank you for your reply, although we still do not understand the logic.
In the same context, when do ages change to X+1 instead of just X?
I hope I am not being ignorant or rude.

I explain simply.
The Japanese Buddhist memorial reckoning system is the same as that of the traditional age reckoning system (Kazoe-doshi 数え年）.
A sufficient explanation may imply complicated religious histories of the East-asian world, and I, myself, don’t know all aspects of these religious customs.
Please refer to this article:
https://en.wikipedia.org/wiki/East_Asian_age_reckoning

However, as practical knowledge, it will be sufficient if you know the followings:
- the 1st memorial of death is at the time of death
- the 2nd anniversary (1 year after, also called in particular the 1st memorial day, 一周忌 isshuuki in Japanese)
- the 3rd anniversary (2 years after)
- the 7th anniversary (6 years after)
- the 13th anniversary (12 years after)
and so on…, but the others seem to be not a common practice in our days...

start from one, not from zero.
add one, when new year's day comes.

It may be regional, but a lot of people seem to do the 13th anniversary memorial 13 years after the death. So your friend's memorial might take place some time around November 2017 instead of 2016.
http://www.sougisupport.net/s_after_07.html

But people aren't that accurate. Also, if they don't follow Buddism (for example, if they are Japanese Christians), they won't be doing the 13th anniversary memorial.

If you can tell us why you're asking, perhaps someone may be able to help you better.

"a lot of people seem to do the 13th anniversary memorial 13 years after the death. "
No. that is not true.

No. that is not true.

Then what did you think about the link I posted? I was only trying to explain what the link says. I would appreciate your help.

(translation)
貼りつけたURLの解説を書いただけのつもりだったのですが、URLについてはどう考えればいいのでしょう？ ご教授いただければありがたいです。

that link is an advertise.
年忌法要は、亡くなった翌年の祥月命日に行う一周忌、翌々年（死後2年目）に行う三回忌、死後7年目に行う七回忌とつづき

it is wrong. 七回忌 is 6th.
how to count from 三回忌(2nd) to 七回忌 (7th ?) by the web site way. please count the years using your fingers.
一周忌 is 二回忌.

Thank you, ken. I suppose the memorial company is doing it the wrong way.