Some help, please.
After almost 2 hours I really seemed to be making inroads and had about half the grid filled. My problem became apparent when I ran out of possible locations for the tetrahedral number.
I'll try to explain how that happened.
I originally had 1, 4, 10, 20 & 35 as possible locations. 1&4 were discounted due to powers allocations, I have 10 as one of the locations for triangular numbers. So I had 20 & 35 remaining.
For property 'm' I had possible locations 14, 34, 35 & 38; for property 'o' I had possible locations 2, 14, 20 & 35. A total of 6 locations are required for those 2 properties, which means that all of those locations would be used for 'm' & 'o'...