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A109673
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Hexagonal pyramid related to Prouhet-Tarry problem.
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6
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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
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,5
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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, ...
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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].
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EXAMPLE
| 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 ....
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CROSSREFS
| Sequence in context: A109393 A030348 A143811 * A023591 A165661 A107711
Adjacent sequences: A109670 A109671 A109672 * A109674 A109675 A109676
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KEYWORD
| nonn,tabf,easy
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AUTHOR
| Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Aug 07 2005
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