Comments on A065078 Wouter Meeussen (wouter.meeussen(AT)vandemoortele.com), Nov 09 2001 Bottom plane of pyramid T[x,y,z=0] contains all 1's They are considered all equivalent starting points. x= 0 1 1 1 1 2 1 1 1 3 1 1 1 1 / / / / y=0 1 2 3 First layer above this (so with z=1 in T[x,y,z=1]) is x= 0 . 1 . 1 2 . 2 3 3 . 3 7 8 / / / / y=0 1 2 3 The second layer above the bottom plane, z=2 x= 0 . 1 . . 2 . . 3 3 . . 10 18 / / / / y=0 1 2 3 and finaly, the top layer at z=3: x= 0 . 1 . . 2 . . . 3 . . . 18 / / / / y=0 1 2 3 so, the 'top'-plane T[x,y,y] reads 1 1 (1) 1 (2) ((3)) 1 (3) ((10)) (((18))) where the number of brackets designates the z-level.