Help please!

[Juss]

I am doing some university maths and need a bit help .... those two tasks:

1) (n^3 +5n) / 6 = ? I need to make a progression formula to here. For example 1*4+2*7+3*10+ ....n ( 3n+1 ) = n ( n+1 ) ^ 2 In my case, I got the right side and need to make the left one .

2) (4^n +15n -1)/ 9 = ?
Same thing here Hope you know how to do it

Whoever is able to solve those, will be respected by me for rest of my life
( I need to make up the formulas and than prove them with mathematical induction, but you can skip the induction part, just try to make up the formula)

[M16]

I don't entirely understand. Can you clarify a bit and then I can maybe try it out?