Problem 60571. Find polygonal numbers that are Blum integers

A polygonal number is the number of dots arranged in the shape of a regular polygon. For example, 15 is a triangular number because dots can be arranged in the shape of a triangle with rows of 1, 2, 3, 4, and 5 dots. The number 16 is a square number because dots can be arranged in four rows of four.
A Blum integer is a semiprime—that is, the product of two distinct primes—whose factors have the form 4k+3 for some integer k. The number 21 is a Blum integer because its two prime factors, 3 and 7, have the form 4k+3 with k = 0 and k = 1.
Recently JessicaR had occasion to point out the properties of the number 57 to me. She observed, among other things, that 57 is both a Blum integer (3x19) and an icosagonal (i.e., 20-gonal) number.
Write a function that takes as input a maximum value x and a number of sides n and returns the largest n-gonal number (i.e., polygonal number with n sides) that is a Blum integer. If there are no numbers in the range 1 to x that work, return y = [].
Solve

Solution Stats

61.54% Correct | 38.46% Incorrect
Last Solution submitted on Jul 18, 2024

Solution Comments

Show comments

Problem Recent Solvers6

Suggested Problems

More from this Author269

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!