what is the answer to this sequence/puzzle? 15 11 2 5 19 8 9 1 15

Question

I am trying to figure out what these numbers mean. A friend gave them to me and already knows, but is expecting the answer from me. I see how they could add up or into each other, but am unsure of my math skills. I will appreciate any feedback or answers given. Thank You.

Answer 1

I don't see any numerical relationships, or consistent pattern, but I note that all the numbers are less than 26, so perhaps they are the position of letters of the alphabet: O K B E S H I A O (anagram of HE IS A BOOK, for example). These could be the initial letters of something meaningful to you or they could be a code. There are also 9 of them, which may indicate a complete set of 9, rather than a series. If there had been 7, for example, I would have thought of the days of the week (I've actually seen this one); or, another example, if there had been 12, the months of the year.