What would be the next 3 letters to this sequence: H B N A I E P R O?

Question

Tell me how'd you get it... No wild guesses please and I don't need an "I don't know" or the likes for an answer...

Answer 1

Imagine you have three rows. Allocate the letters to the rows in order:

H
B
N

HA
BI
NE

HAP
BIR
NEO

Look like the beginnings of words?

HAP(P)Y
BIR(T)HDAY
NEO(P)ETS

Answer 2

Analytically, I do not see a pattern in the order of these letters, based on the alphabet itself. But you've been given nine letters and asked for three more, making a total of twelve. This, to me, suggests the months of the year. Other sequences of twelve do not normally have a set order (the apostles, for example), but the months certainly do. I suspect that these letters are the initial letters of words that form some sort of sequence related to the months. It's not the names of the months themselves in any language that I know, and it's also not birthstones, as far as I can tell. But start from there to see if you can find the answer.