Thread: what is a triangular number ?

what is a triangular number ????
badly stuck ...

A triangular number is the sum of the n natural numbers from 1 to n. The sequence of triangular numbers for n = 1, 2, 3... is: 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ....

Hello, sportychick1912!

What is a triangular number?

They arise from triangular arrays of objects.

Code:

                                              o
                                 o           o o
                      o         o o         o o o
             o       o o       o o o       o o o o
      o     o o     o o o     o o o o     o o o o o

      1      3        6         10           15

And we have:

. .