# Deduce the next term in this sequence: m,n,a,z,l,o,b,y,k,p,c,x,j

This is the question :

m,n,a,z,l,o,b,y,k,p,c,x,j

In the letter series above, which one of the following choices logically follows

d

k

m

q

r

Thanks

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I have no idea if this is right, but: 2nd letter is n jump 4 get o jump 4 get p jump 4 get ... q ? –  Thomas Apr 21 '12 at 20:28
Is this your math homework? –  Rasmus Apr 21 '12 at 20:30
There are uncountably many sequences starting with those letters. This isn't mathematics, it's vague guesswork. –  user5137 Apr 29 '12 at 5:43

There are four sequences here, one of which is suggested by @Thomas:

• m,l,k,j (alphabet counting backwards)
• n,o,p (this one will give you the next letter)
• a,b,c
• z,y,x
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Be careful! It need not be $q$. Recently I have seen this sequence: $m,n,a,z,l,o,b,y,k,p,c,x,j,j,j,j,j,j,j,...$ (and somewhere there followed some $x$, but unfortunately I do not remember the exact positions and how many of them were there in total).

To give an explanation: You have implicitly assumed that there is a rule that generates your sequence. Many mathematicians do that, and in your case it might even be correct. But in most cases it is wrong. A finite formula defines an infinite sequence. But an infinite sequence can never (that means "never" and not "at a certain time") define a finite formula.

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It's $q$. Look at the pairs of numbers. One sequence is going up and down from the middle $(m,n), (l,o) ,(k,p), (j,?)$ while the other is going down and up from the end $(a,z) , (b,y), (c,x)$.

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converting the series in numbers gives

$$13,14,1,26,12,15,2,25,11,16,3,24,10$$ $$13,14 ,,,,1,26,12,15,,,,,2,25,11,16,,,,,3,24,10$$ $$0,27,13,14 ,,,,1,26,12,15,,,,,2,25,11,16,,,,,3,24,10,X$$

its the series,

$$a,b,c,d,,,,(a+1),(b-1),(c-1),(d+1),,,,(a+2),(b-2),(c-2),(d+2),,,,(so-on)$$ The pattern is very obvious, X=17, i.e. the alphabet q

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