I've been looking more at the tetrahedral numbers (4,10,20), and I may have found something. Look at these grids. Basically the white columns are the seeds, and each value is equal to the sum of the one above and one to the left of it. By default, the first row is a 1. Then the top left box is just regular numbers seeded by a 1. The highlighted column in that box are the tetrahedral numbers. The highlighted column in the next is square numbers. Then the next is pentagonal numbers, then hexagonal, heptagonal, etc. If you look at the highlighted row, then you can see that there is a simple pattern to get from grid to grid. (ie, from 1 to 2 you subtract 1, from 2 to 3 you subtract 2, from 3 to 4 you subtract 3) so you can easily navigate through these grids. Also for each box n, the first column is all the numbers where mod n is the seed. So maybe we could start with a zero seed (cuz then its divisible) or something like that. Or we could use the identity n*n = T(n) + T(n-1) where T(n) is the nth triangular number. Get the number in the square grid and translate it to a different grid and do stuff. Also these grids can be extended into the negative (I'll get on that).
Basically the idea is to get our number. E would be the seed and D would be the start column. Then we can use some of these identities to navigate around to the grid where we are in the A column with a 0 seed.