Sequence Pattern Detector

For 2; 4; 6; 8 the common difference is 2. For 3; 9; 27; 81 the common ratio is 3. Arithmetic detection runs first, so a constant sequence is arithmetic with difference zero.

Consecutive differences must be exactly equal as JavaScript Number values. Otherwise every consecutive ratio must differ from the first by strictly less than 1e-10. Number rounding, division by zero and extreme magnitudes can affect detection. The result is a simple diagnostic, not a proof or prediction; polynomial, Fibonacci, repeating and alternating patterns are not inferred.