Why to multiply N-1 C 1 with f(n-2)

#1

We need to make pair or single so we can go for n-1 and n-2 but what is the use of Combination as we need to count ways

#2

For single you are correct the number of ways will be n-1 only.
but for pairs the number of ways will not be n-2 for example let the sequence is : [a,b,c] here n=3 but no of pairs will be (a,b), (b,c) and (a,c) which is (nC2=3) not n-1=1.

#3

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