Arithmetic and Geometric Series Calculator
Find any term and the sum of the first n terms of an arithmetic or geometric sequence.
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Sum of n terms
- nth term
- First terms
- Infinite sum
- Work
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Sequence and Series Formulas
Arithmetic: aₙ = a₁ + (n − 1)d Sₙ = n(a₁ + aₙ) ÷ 2
Geometric: aₙ = a₁rⁿ⁻¹ Sₙ = a₁(1 − rⁿ) ÷ (1 − r) S∞ = a₁ ÷ (1 − r) when |r| < 1
Worked Example
Tips
Compound interest is a geometric sequence; a savings plan that adds the same amount each month without interest is arithmetic.