Inductive definations and sequences

so how do i find the inductive definitions for this question
" Write down the first five term of the sequnce and then write the inductive definition for it:
Ur=1/6r(r+1)(2r+1)"
the first part is obviously easy but i get stuck on the inductive definition. Is there a faster way to solve this question rather than the trial and error method...

(edited 5 years ago)

Reply 1

username3249896

https://en.wikipedia.org/wiki/Recursive_definition

1,5,14,30,55,91

What can you see about the terms? The difference between the terms? Write the inductive definition