A number series that is hard to figure out what the next term is, because one has no idea what the formula used to generate the numbers is.
In the Trump series 1, 2, 4, …, what is the next term? Is it 8, because the next term is twice the previous term? Is it 7, because the difference between two neighboring terms increases by 1 each time? Or, is it the number 9 (which is based on the formula 1/6(n – 1)(n – 2)(n – 3) + 2ⁿ⁻¹ when n = 4)?
by MathPlus February 19, 2017