# What is the next number in the given series?

I know that next number questions are not popular here, but this one is tough and I couldn't figure out the pattern. To give an idea one of the questions had a pattern of Prime(Fib(n)).

So this is the series:

0, 0, 2, 6, 12, 21, 34, 51

What is the next number in the series ?

• Welcome to Puzzling.SE! If this puzzle was taken from somewhere, please make sure you provide details of where it came from, ensure you have the original author's permission and that it does not come from an active competition or exam – Dmihawk Dec 5 '18 at 20:29
• @papabiceps If Mathematics didn't get you an answer, why do you think you will get one here? – rhsquared Dec 5 '18 at 23:34
• Just posted here, to see if I can get an answer. – papabiceps Dec 5 '18 at 23:36

Here's a relatively simple formula that works (starting $$n=0$$)
$$a_n = n^2 - n + (\max \{ 0, n-4\})^2$$
$$a_8 = 8^2 - 8 + 4^2 = 72$$