Sequence Calculator

Type the terms you have and this looks for the rule behind them: a common difference, a common ratio, a Fibonacci style sum of the two terms before, a polynomial up to degree four, or a general two term recurrence fitted to the numbers. When one fits it gives the formula, the term you asked for, the sum to that point and the next five terms, along with how many of your terms actually confirmed the rule rather than being used to work it out. When nothing fits it says so and prints the differences and ratios instead of forcing a pattern. A second mode builds a sequence from a first term and a difference or ratio you already know.