A109673 Hexagonal pyramid related to Prouhet-Tarry problem.

1, 1, 1, 1, 3, 1, 1, 1, 1, 2, 1, 2, 8, 8, 2, 1, 8, 15, 8, 1, 2, 8, 8, 2, 1, 2, 1, 1, 3, 3, 1, 3, 15, 24, 15, 3, 3, 24, 60, 60, 24, 3, 1, 15, 60, 93, 60, 15, 1, 3, 24, 60, 60, 24, 3, 3, 15, 24, 15, 3, 1, 3, 3, 1, 1, 4, 6, 4, 1, 4, 24, 52, 52, 24, 4, 6, 52, 160, 228, 160, 52, 6, 4, 52

Offset: 0

Author

Philippe Deléham, Aug 07 2005

Keywords

• nonn
• tabf
• easy

Comments

Entries of slices [n,n] in A109672, read by rows.

Greatest numbers in each slice (central numbers) form A002893 : 1, 3, 15, 93, 639, ...

Examples

			Slice [0, 0]:
... 1 ...
Slice [1,1]:
... 1 1 ...
.. 1 3 1 ...
... 1 1 ...
Slice [2,2]:
.... 1 2 1 ...
... 2 8 8 2 ...
.. 1 8 15 8 1 ...
... 2 8 8 2 ...
.... 1 2 1 ....
Slice [3,3]:
...... 1 3 3 1 .....
.... 3 15 24 15 3 ...
... 3 24 60 60 24 3 ...
.. 1 15 60 93 60 15 1 ...
... 3 24 60 60 24 3 ...
.... 3 15 24 15 3 ....
...... 1 3 3 1 ....
		

Formula

Sum of terms in slice [n, n] = 3^(2n); example : 1+2+1+2+8+15+8+1+2+8+8+2+1+2+1 = 3^4 = 81 for the slice [2, 2].