Sum of Linear Sequence Calculator

Use our sum of linear sequence calculator to find the sum of a linear sequence (arithmetic sequence) quickly. Includes what is a linear sequence, the sum of linear sequence formula, the linear sum formula, and how to calculate sum of series step by step.

Initial value
First term (a₁).
Difference
Common difference (d).
Periods
Number of terms (n).
Results
Final value
Last term in the sequence: aₙ = a₁ + (n−1)d.
Sum
Sum of terms: Sₙ = n/2 × (a₁ + aₙ).
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What is a Linear Sequence?

A linear sequence is a sequence where the difference between consecutive terms is constant. This is also called an arithmetic sequence.

If you’re asking what is a linear sequence, think of a pattern like 3, 7, 11, 15, … where each term increases by the same amount (+4).

The sum of a linear sequence is the total of the first n terms. This sum of linear sequence calculator uses the standard linear sum formula to compute it instantly.

Sum of Linear Sequence Formula

To calculate the sum of a linear sequence (arithmetic series), you can use the first term, last term, and number of terms, or use the first term and common difference.

Sum using first and last term =
S_n = n/2 · (a_1 + a_n)

Where a1 is the first term, an is the nth (last) term, and n is the number of terms.

Sum using first term and difference =
S_n = n/2 · (2a_1 + (n - 1)d)

Where d is the constant difference between terms.

S_n
= Sum of the first n terms (sum of series)
n
= Number of terms
a_1
= First term
a_n
= nth term (last term)
d
= Common difference (constant step)
Sum of linear sequence example
3, 7, 11, 15 (n=4) → S_4 = 4/2 · (3 + 15) = 2 · 18 = 36

This is how to calculate sum of series for a simple linear sequence.

Linear sum formula (with difference)
a1=5, d=2, n=6 → S_6 = 6/2 · (2·5 + 5·2) = 3 · 20 = 60

Uses S_n = n/2 · (2a1 + (n-1)d).

How to Use the Sum of Linear Sequence Calculator

  1. 1

    Enter the first term (a₁).

  2. 2

    Enter the common difference (d) OR enter the last term (aₙ) if your calculator supports it.

  3. 3

    Enter the number of terms (n).

  4. 4

    The calculator returns the sum of the linear sequence using the sum of linear sequence formula.

Frequently Asked Questions

What is a linear sequence?

A linear (arithmetic) sequence is a sequence where the difference between consecutive terms is constant.

What is the sum of linear sequence formula?

S_n = n/2 · (a_1 + a_n). Another equivalent form is S_n = n/2 · (2a_1 + (n-1)d).

How to calculate sum of series for a linear sequence?

Find a1, an (or d), and n, then apply S_n = n/2 · (a_1 + a_n).

What is the linear sum formula?

For an arithmetic series: S_n = n/2 · (a_1 + a_n) or S_n = n/2 · (2a_1 + (n-1)d).

Is this a sum of linear sequence calculator?

Yes—enter your sequence inputs and it outputs the sum instantly.