Ok so I have an array similar to the following.

array = [a,b,c,d,e,f,g,h,i,j,k,l];

This array is used to generate a table that I will display by distributing the array onto a grid based on the number of columns and rows that the table has. I'm trying to create a for loop that will push to an array the desired index values for new cells when adding a column to the table.

//Know Values//
selectedColumn = **A**; (2) // index of selected column
numRows = **B**;        (3) // derived from array length so 1 less than actual rows displayed
numColumns = **C**;     (2) // derived from array length so 1 less than actual columns displayed

//Mock Table Display, distributing array into rows//
index    0, 1, 2, 3
row0     a, b, c, d,    A * (X) = 2
index    4, 5, 6, 7
row1     e, f, g, h,    A * (X) = 6
index    8, 9,10,11
row2     i, j, k, l     A * (X) = 10

indexValues = [2, 6, 10]

The chart above is hopefully able to describe what I'm referring to. I would like a value for X that works for any number of columns and rows to return the correct index value. I assume X will need to be a mathematic expression involving A and C. Currently using row in a loop to determine which row is being calculated for.

  for (let row = 0; row < numRows; row++) {
    let index = (row + 1) * selectedColumn;
    indexValues.push(index);
  }