Which of the following sequences is different from the rest?

Let us analyze each sequence:
* Sequence a ($1,4,9,16$): This represents squares of consecutive natural numbers: $1^2,2^2,3^2,4^2$.
* Sequence b ($1,8,27,64$): This represents cubes of consecutive natural numbers: $1^3,2^3,3^3,4^3$.
* Sequence d ($1,16,81,256$): This represents fourth powers of consecutive natural numbers: $1^4,2^4,3^4,4^4$.
* Sequence c ($2,6,12,23$): The differences between consecutive terms are $4,6,11$, which does not follow a standard pure power pattern like the others. Thus, it is the odd one out.