Arithmetic Sequence Calculator
n-th term and sum of an arithmetic sequence.
How it works
aₙ = a₁ + (n−1)d; Sₙ = n(a₁ + aₙ) ÷ 2
A sequence with a constant difference between consecutive terms. n must be a positive integer.
Worked example
First term 3, common difference 5, 10 terms:
a₁₀ = 3 + 9×5 = 48; sum S₁₀ = 10×(3+48) ÷ 2 = 255.
Notes and limitations
General term aₙ = a₁ + (n−1)d; sum Sₙ = n(a₁+aₙ)/2. Arithmetic sequences model fixed increments such as annual raises or tiered pricing.