Between each pair of terms in this sequence is the amount the sequence is decreasing by. The 𝒏th term refers to a term's position in the sequence, for example, the first term has 𝒏 = 1, the second ...

You get the next term by adding three to the previous term. The rule is + 3. So you can find any term if you know the previous term. But how do you find the term for any position without working out ...

Random digits are collected one at a time until a given k-digit sequence is obtained, or, more generally, until one of several k-digit sequences is obtained. In the former case, a recursive formula is ...