what is a triangular number ????
badly stuck ...
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:
. . $\displaystyle \begin{array}{ccccc}T_1 &=& 1 &=& 1 \\
T_2 &=& 1+2 &=& 3 \\ T_3 &=&1+2+3 &=& 6 \\ T_4 &=&1+2+3+4 &=&10 \\ T_5 &=& 1+2+3+4+5 &=&15 \\ \vdots & & \vdots & & \vdots \\
T_n &=& 1+2+3+\hdots+n &=&\dfrac{n(n+1)}{2}\end{array}$