Sigma or Summation function in Excel

Question

Given a value (in a cell), calculate a formula like this:

Ʃ(3i+1) for i from 0 to the value specified in the cell.

SUM(), SERIESSUM() are not suitable in thi

Answer 1

Use the array formula:

=SUM(3*ROW(INDIRECT("1:" & A1))+1)+1

Array formulas must be entered with Ctrl + Shift + Enter rather than just the Enter key.