Summation Formulas

[ChaoticLlama]

........................20
I know that for Σ i³ you would just use [{20(20 + 1)}/2]² to find the sum
........................ i=1

But is there any way to use the formula for a summation whose starting value is not 1?
For example:

20
Σ i³
i=4

 

[soroban]

Hello, ChaoticLlama!

. . . . . . . . . . . 20
I know that for Σ i³ you would just use [{20(20 + 1)}/2]² to find the sum
. . . . . . . . . . .i=1

But is there any way to use the formula for a summation whose starting value is not 1?
For example:

20
Σ i³
i=4

Yes . . . Find the sum from 1 to 20, then subtract the sum from 1 to 3.

 

[ChaoticLlama]

Doh!

Thanks for your help