Project Euler problem 12 Python
To avoid spoiling the problem for you, I'll offer some hints.

Hint 1:


   Have you read the Wikipedia article about the triangular numbers? It's always worth doing a bit of research into the mathematical background of a Project Euler problem.


Hint 2:


   There is a mathematical formula for the \$n\$th triangular number, namely \${1\over2}n(n+1)\$.


Hint 3:


   What do you know about the divisors of \${1\over2}n(n+1)\$? Try out some small examples and see if there is a pattern.


Hint 4:


   When a problem requires you to establish some facts about the divisors of all the numbers in a range, then what you need is a sieve.