If I have 56 nuclotide bases and each DNA model can contain 4 different bases, how many different combinations of DNA models can I have?
nCr[56 + 4 - 1], 4 =59C4 =455,126
My understanding is that the 4 bases can be repeated, such as:AAAA, CCCC, GGGG and TTTT. The formula I used is the Binomial expansion with repeats allowed.
You could be right. I have a Math Dictionary and gives the following:
1-Combinations with repetitions: Each element can be chosen more than once for a particular combination. The number of possible combinations is then [n + r -1], r.
Example n=4, r=2 a, b, c, d: aa, ab, ac, ad,
bb, bc, bd,
[4 + 2 -1], 2 =5C2 = 10