Calculators
Pronic Number Calculator
Calculate the nth pronic number exactly as the product of consecutive integers, privately in your browser.
Multiply consecutive integers to count a rectangle of dots.
The nth pronic number is P(n) = n × (n + 1). These are also called oblong numbers: n rows of n + 1 dots form a rectangle. For n = 0 through 5 the values are 0, 2, 6, 12, 20, and 30. For n = 10, P(10) = 10 × 11 = 110. Each value is twice the nth triangular number and is even because one of two consecutive integers is even. Enter a non-negative index of up to 100 digits; leading zeros are accepted. Signs, commas, decimals, and scientific notation are rejected. Browser BigInt arithmetic keeps every digit exact. This calculator finds a value from its index; it does not test whether an arbitrary number belongs to the sequence. All processing stays in your browser.
Frequently Asked Questions
Everything you need to know about this tool, how it works, and privacy.
What is a pronic number?
A pronic or oblong number is the product of consecutive non-negative integers n and n + 1. Starting at index zero, the sequence is 0, 2, 6, 12, 20, 30.
How do I calculate the nth pronic number?
Use P(n) = n × (n + 1). At index 10, multiply 10 by 11 to get 110. This tool indexes the sequence from zero.
How are pronic and triangular numbers related?
P(n) is twice T(n), since the nth triangular number is n × (n + 1) ÷ 2. Every pronic number is even.
Which inputs are accepted?
Enter a non-negative whole index of 1 to 100 digits. Zero returns zero and leading zeros are accepted. Decimals, negative values, commas and exponent notation are rejected.
Are large results exact and private?
Yes. BigInt arithmetic preserves the exact integer result, and calculations happen in your browser without uploading the input.