Hello!

I've got this problem.

18. Consider the following four equations:

1) 1 = 1

2) 2+3+4 = 1+8

3) 5+6+7+8+9 = 8+27

4) 10+11+12+13+14+15+16 = 27+64

Conjecture the general formula suggested by these four equations, and prove your conjecture.

Any help would be appreciated

Thanks!