Identify if the following sequence is arithmetic, geometric, or none of them. In the case of an arithmetic sequence, determine its common difference, and in the case of a geometric sequence, determine its common ratio.

a_n = n³ + 1

Rewrite and simplify the given recurring decimal as a whole number.

For the given infinite series, evaluate the sum.

The first term (a₁) and the common ratio (r) of a geometric sequence are given. Find the specified term using the general term (n^th term) formula.

Find a₁₅ when a₁ = 4, r = -3.

The recursive formula and the first term of a geometric sequence are given. Find the first eight terms.

a_n = 2a_n-1, a₁  = 5

Consider this repeating decimal 8.3... (repeating 3). Express this as a fraction by adding the whole number to a sum of a geometric series.