The 7 Sequence Types You Need to Know for Quant Interviews
By Sample_User on Fri May 09 2025
Outside of math classes and quant interviews, sequences rarely spark lively conversation—let alone get mentioned at all.
But they play a crucial role in aptitude tests and technical interviews, especially when assessing pattern recognition and reasoning skills.
So today, I’m breaking down the seven most common types of sequences you’re likely to encounter in math and quantitative assessments—arranged from the simplest to the most challenging:
1. Arithmetic Sequences
- Pattern: Each term increases by a fixed difference.
- Example:
3, 6, 9, 12, ... - Tests: Linear growth recognition.
2. Geometric Sequences
- Pattern: Each term is multiplied by a constant ratio.
- Example:
2, 6, 18, 54, ...(×3) - Tests: Understanding of exponential scaling.
3. Alternating Patterns
- Pattern: Terms follow different rules based on their position (e.g., odd/even index).
- Example:
2, 4, 3, 6, 4, 8, ...(even-index adds 2, odd-index adds 1) - Tests: Ability to spot layered logic.
4. Recursive Sequences
- Pattern: Each term is derived from one or more previous terms.
- Example:
1, 1, 2, 3, 5, 8, ...(Fibonacci) - Tests: Abstraction and pattern memory.
5. Polynomial Sequences
- Pattern: Differences between terms form a consistent pattern (e.g., second differences are constant).
- Example:
1, 4, 9, 16, 25, ...(squares) - Tests: Recognizing nonlinear relationships.
6. Prime / Factorial / Power-Based Sequences
- Prime:
2, 3, 5, 7, 11, ... - Factorial:
1, 2, 6, 24, 120, ... - Powers:
2, 4, 8, 16, 32, ... - Tests: Number theory instincts.
7. Non-Numerical or Trick Patterns
- Pattern: May involve language, symbols, or visual rules rather than pure arithmetic.
- Example: Number of letters in the English word for each number.
- Tests: Lateral thinking and pattern flexibility.
From my experience, alternating and polynomial sequences tend to trip people up the most—they’re deceptively complex and easy to overlook.
Knowing these seven foundational types will prepare you for nearly any sequence problem that comes your way, whether on a test, in an interview, or just to impress your mathematically inclined friends.