What is the next number in the series 81 90 83 94 82 108?

Answer 1

It is possible to find a polynomial of order 6 that will generate the above sequence of numbers and ANY seventh number. And, there are non-polynomial rules that will do the same.

The simplest polynomial is

Un = (177n5 - 3030n4 + 19475n3 - 57990n2 + 78688n - 27600)/120 for n = 1, 2, 3, ... and, according to this rule, the next number is 512.