Mixed rules: Two alternating rules (+3, ×2, +3, ×2...)
Always check the differences between consecutive numbers first. If those differences also form a pattern, you have a second-order sequence.
The Difference Method
Write out the gaps between each number. If the gaps aren't constant, write the gaps between the gaps. Most sequences reveal themselves within two rounds of this.
Speed Tips
Check if numbers are going up or down — narrows your options immediately
Check if numbers are doubling or halving — geometric sequences are common
If stuck, check if every other number forms its own simpler sequence
Put it into practice
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