The sequence below is the start of the triangular number sequence.Work out the next two number terms in the sequence.

The triangular number sequence is generated by the formula:

$T_n = \frac{n(n + 1)}{2}$

Where $T_n$ is the $n$-th triangular number.

Given Sequence

The initial terms of the triangular number sequence are:

1. $T_1 = 1$
2. $T_2 = 3$
3. $T_3 = 6$
4. $T_4 = 10$
5. $T_5 = 15$

Next Two Terms

To find the next two number terms, we will calculate $T_6$ and $T_7$:

1. Calculate $T_6$: $T_6 = \frac{6(6 + 1)}{2} = \frac{6 \times 7}{2} = \frac{42}{2} = 21$

2. Calculate $T_7$: $T_7 = \frac{7(7 + 1)}{2} = \frac{7 \times 8}{2} = \frac{56}{2} = 28$

Final Answer

The next two terms in the triangular number sequence are 21 and 28.