Summations that are functions of n

Question

How do I calculate this with i being n/4

n

f(n) = ∑ (i)

i=n/4

Answer 1

Your question and/or notation is/are not clear.

However, ∑k for k=1 to n is n(n+1)/2.

If the summand (k) is multiplied by a constant, the constant simply multiplies the sum.

If the step size is decreased, the easiest way to figure the sum is to do a change of variable.

If this does not help AND you can clarify your question, please comment and I will try to help further.