Arithmetic Sequence Calculator
Find the nth term and sum of an arithmetic sequence. Calculate any term or partial sum given the first term and common difference.
Enter the first term, common difference, and term number.
Arithmetic Sequence Formulas
nth term: an = a₁ + (n − 1) × d
Sum of first n terms: Sn = n/2 × (2a₁ + (n − 1) × d) = n/2 × (a₁ + an)
Sum of first n terms: Sn = n/2 × (2a₁ + (n − 1) × d) = n/2 × (a₁ + an)
An arithmetic sequence is a sequence of numbers where the difference between consecutive terms is constant. This constant is called the common difference (d).
Example: a₁ = 2, d = 3, find a₁₀ and S₁₀
a₁₀ = 2 + (10 − 1) × 3 = 2 + 27 = 29
S₁₀ = 10/2 × (2 + 29) = 5 × 31 = 155
Sequence: 2, 5, 8, 11, 14, 17, 20, 23, 26, 29
a₁₀ = 2 + (10 − 1) × 3 = 2 + 27 = 29
S₁₀ = 10/2 × (2 + 29) = 5 × 31 = 155
Sequence: 2, 5, 8, 11, 14, 17, 20, 23, 26, 29
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Last updated: 2026-08-08