Triangular numbers—which are the subject of Cody Problems 5, 291, 44289, 44732, 45833, 55680, 55695, and 55705—are the sums of consecutive integers. For example, the 10th triangular number is the sum of the numbers 1 to 10, or 55.
Lunar addition, which is the subject of Cody Problem 44785, involves taking the largest digit in the sum. For example, 1+3 = 3, 3+6 = 6, 13+51 = 53, and 428+620 = 628.
Write a function to compute the nth lunar triangular number without duplicating any terms. For example, the 10th lunar triangular number is 1+2+3+4+5+6+7+8+9+10 = 19. The 11th lunar triangular number is also 19, but because it is a duplicate, it would not be listed in this sequence. Express the answer as a character string.
Solve

Solution Stats

7 Solutions

7 Solvers

Last Solution submitted on Oct 13, 2026

Last 200 Solutions

Solution Comments

Show comments

Problem Recent Solvers7

Chris Cleveland George Berken goc3 Christian Schröder

Suggested Problems

More from this Author329

Community Treasure Hunt

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

Start Hunting!