# What is next letter in sequence: B, D, G, J, L, ___?

My answer is P. But I am not sure as there is not sufficient data to support this.

B(2), ____, G(7), ____, L(12), _____ (alternating sequence of difference 5: 2, 7, 12, 17,...)

____, D(4), ____, J(10), ____, P(16) (alternating sequence of difference 6: 4, 10, 16, ...)

Is this correct answer? Or can someone come up with different answer with better logic?

• Welcome to Puzzling.SE! Where did you get this puzzle from? If it's not a puzzle you created yourself, you need to credit the original source, otherwise it can be considered plagiarism. Oct 25, 2023 at 16:51
• My friend sent it to me. He was asked in an in-person interview for the trader role. Oct 25, 2023 at 16:53
• I think 2 datapoints for the even-indexed letters is not enough to support your idea. That said, this is a pretty short sequence Oct 25, 2023 at 21:53
• If it's an interview question it might be purposefully designed not to have an obvious answer, to get an idea about how the candidate is thinking an exploring options. Oct 26, 2023 at 5:45

Maybe the answer is

N

because

the sequence consists of every other consonant starting with B:

(a) B C D (e) F G H (i) J K L M N (o) P Q R S ….

I think the next letter could be

M

As these are

The "voiced" consonants (consonants which require the use of vocal cords) in alphabetical order.

Reference

I agree strongly with the comments and the trend of the answers so far: This is likely a question without a clear answer that was asked to try to learn something about the interview candidate's thinking/pattern recognition processes. The pattern isn't simple enough to confidently identify a single answer. If it had been every 3rd letter, B,E,H,K,N,__ for instance, then while other patterns could definitely be identified, the obvious answer would be Q.

This pattern isn't that simple, and I can't see how any of the solutions given are better or worse than the others.

My solution (I will suggest that as an interviewer I would not be thrilled with this as anything other than an initial observation.): M

I noticed that the patterns of skipped letters is 1 - 2 - 2 - 1. This could repeat.
B (skip 1) D (skip 2) G (skip 2) J (skip 1) L (skip 1) M

Again, not a clever pattern and not well supported by the available data - I just felt that I should include my own solution to the problem rather than a just commentary about the questioner's reasoning.

• Why would the pattern repeat every 4 steps when the simpler option of repeating every 3 steps is also possible? Oct 26, 2023 at 11:27
• That's just another of the many options. Actually, 1-2-2-1-1-2-2-1 looks prettier to me than 1-2-2-1-2-2. Oct 26, 2023 at 11:28
• @JaapScherphuis That's kind of the point. You saw the 1 as the new beginning of a repeating cycle while I saw it as the end of a symmetric cycle. Oct 28, 2023 at 12:43

It could be O

Convert to integers, 2, 4, 7, 10, 13.
deltas are: 2, 3, 3, 2.
continue pattern 2, 3, 3, 2, 3, 3 -> letter L+3 = O

Or it could be N

deltas are: 2, 3, 3, 2.
continue with doubles 2, 3, 3, 2, 2, 3, 3, 2 => letter L+2 = N

Or maybe L

deltas are: 2, 3, 3, 2,
2nd deltas are: 1, 0, -1.
continue 1, 0, -1, -2, deltas are 2, 3, 3, 2, 0 => letter L+0 = L

Or maybe O after all

deltas are: 2, 3, 3, 2,
follow Morse-Thue pattern 2332322332232332... => letter L+3 = O

Or it could be P

There are two interleaved sequences:
B, G, L: progression 5
D, J, ?: progression 6 => letter J+6 = P

As infinitezero and Jason Patterson suggest, the question is not to find the correct answer but to see how you think.

I think it is M or N or O. Reasons below. (BTW my reasoning might be weird and difficult to understand).

Because:

BDGJL

My way of doing it is kind of using math here. The number is equivalent to the amount of letters that space the "other letters". Says B to D. D is two letter after B. So using this logic:

B+2=D D+3=G G+3=J J+2=L

So to solve this, i need to follow the pattern. Before B was A, so A+1=B. So I think the pattern is. x+1, x+2, x+3, x+3, x+2, x+1.

With that reasoning of the (+1), the answer is M. If you go:

x+2, x+3, x+3, x+2, x+2, then the answer is N.

If you go:

x+2, x+3, x+3, x+2, x+3. Then the answer is O.

As I said before, my reasoning might not be understandable, I understand.