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A206561
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Triangle read by rows: T(n,k) = total sum of parts >= k in all partitions of n.
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11
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1, 4, 2, 9, 5, 3, 20, 13, 7, 4, 35, 23, 15, 9, 5, 66, 47, 31, 19, 11, 6, 105, 75, 53, 35, 23, 13, 7, 176, 131, 93, 66, 42, 27, 15, 8, 270, 203, 151, 106, 74, 49, 31, 17, 9, 420, 323, 241, 178, 126, 86, 56, 35, 19, 10, 616, 477, 365, 272, 200, 140, 98, 63, 39, 21, 11
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OFFSET
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1,2
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COMMENTS
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In the n-th row of the triangle the first differences together with its last term give the n-th row of triangle A138785 (see below):
Row..........: 1 2 3 4 5 ...
--- ---- ------- ------------ ----------------
This triangle: 1; 4, 2; 9, 5, 3; 20, 13, 7, 4; 35, 23, 15, 9, 5; ...
| | /| | /| /| | / | /| /| | / | / | /| /|
| |/ | |/ |/ | |/ |/ |/ | |/ |/ |/ |/ |
A138785......: 1; 2, 2; 4, 2, 3; 7, 6, 3, 4; 12, 8, 6, 4, 5; ... (End)
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LINKS
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FORMULA
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T(n,n) = n, T(n,k) = T(n,k+1) + k * A066633(n,k) for k < n.
T(n,k) = Sum_{i=k..n} A138785(n,i).
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EXAMPLE
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Triangle begins:
1;
4, 2;
9, 5, 3;
20, 13, 7, 4;
35, 23, 15, 9, 5;
66, 47, 31, 19, 11, 6;
105, 75, 53, 35, 23, 13, 7;
...
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MATHEMATICA
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Table[With[{s = IntegerPartitions[n]}, Table[Total@ Flatten@ Map[Select[#, # >= k &] &, s], {k, n}]], {n, 11}] // Flatten (* Michael De Vlieger, Mar 19 2018 *)
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CROSSREFS
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KEYWORD
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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