Which number should come next 4 5 8 17 44?

Answer 1

4 - 5 - 8 - 17 - 45(????) ->>>> (81)

(1,3,9,18,36)

* * * * *

Where did the 45 in the answer above come from? The question has a 44 after the 17. Also, the answer above seems to suggest that the figures in the brackets are the first order differences. That is, 5-4 = 1, 8-5 = 3 and so on.

That would imply that 45-17 = 18. Have I missed something here? I always believed that 45-17 = 28!

Not a very convincing way of answering a question. Change the numbers in the question to suit your answer and then carry out some rather dubious arithmetic to make it work!

So, here is another offer:

Fit the quartic equation:

t(n) = (n4 - 8n3 + 26n2 - 34n + 27)/3 for n = 1, 2, 3, ...

Then t(6) = 109

Not a very pretty answer, admittedly, but at least it is consistent with the question that was asked!