http://www.neuropolis.org/triangle-pyramid-puzzle/
Instead of the pyramid of numbers and tetrahedral numbers … puzzle?
Find two values that meet the following: The number of square pyramids + 1 = number of tetrahedral (square number pyramid consists of consecutive squares, 1 + 4 + 9 + 16 … each layer of the pyramid. Tetrahedral numbers consist of consecutive triangular numbers, 1 +3 +6 +10 +15 … for each layer of the pyramid with a triangular base.) One answer is 55 and 56 What is different?
Another reason is the 285 and 286 285 = 1 +4 9 + … 81 286 = 1 3 6 + … +55 +66
TRIANGLE MYSTERY 2 Ancient Armenian Pyramid FIND TRIANGLES !
