in the sequence we can see that we arrive at the next term by simply adding 30 to the current one, thus
[tex]\stackrel{\textit{Explicit, only requiring argument susbtitution}}{f(n)~~ = ~~n + 30}~\hfill \stackrel{\textit{Recursive, requiring ordinal position}}{f(a)~~ = ~~ a_{n-1}+30}[/tex]
