zhshqzyc
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Number of the combinations
Hi, suppose I have 4 letters A,C,G,T.
I want to use them to create a sequence such as ACTGGTCAAA etc. The length of the sequence is 10.
Would you please tell me how many combinations totally?
Thanks.
I want to use them to create a sequence such as ACTGGTCAAA etc. The length of the sequence is 10.
Would you please tell me how many combinations totally?
Thanks.
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If you have a sequence of n letters comprising of A, C, G, T only, since you have 4 choices for each position the formula is
number of combinations for a of string length n = 4^n
If you have k possible letters instead of 4 the answer is k^n
number of combinations for a of string length n = 4^n
If you have k possible letters instead of 4 the answer is k^n
The link I posted above will show you the formula as well as calculate the value for you.
ASKER
So the result 286 from sch13824 is wrong. How did you get it?
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I withdraw my earlier comment/answer. I incorrectly applied combinations. Phoffric's logic and GwynforWeb's formula of k^n for k items forming a string of n length is correct.
ozo is correct. That was my misapplication. From your example above, ACTGGTCAAA would be the same as CATGGTCAAA (or any sequence that contains 4 As, 2 Cs, 2 Gs , and 2 Ts for that matter).
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