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A109974
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Array read by antidiagonals: sigma_k(n) for n>=1, k>=0.
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5
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1, 2, 1, 2, 3, 1, 3, 4, 5, 1, 2, 7, 10, 9, 1, 4, 6, 21, 28, 17, 1, 2, 12, 26, 73, 82, 33, 1, 4, 8, 50, 126, 273, 244, 65, 1, 3, 15, 50, 252, 626, 1057, 730, 129, 1, 4, 13, 85, 344, 1394, 3126, 4161, 2188, 257, 1, 2, 18, 91, 585, 2402, 8052, 15626, 16513, 6562, 513, 1, 6, 12
(list; table; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Rows sums are A108639. Diagonal sums are A109976. Matrix inverse is A109977.
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FORMULA
| Regarded as a triangle, T(n, k)=if(k<=n, sigma(k-1, n-k+1), 0). - Frank Adams-Watters (FrankTAW(AT)Netscape.net), Jul 17 2006
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EXAMPLE
| Start of array:
1 2 2 3 2 4 ...
1 3 4 7 6 12 ...
1 5 10 21 26 50 ...
1 9 28 73 126 252 ...
1 17 82 273 626 1394 ...
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MATHEMATICA
| rows = 12; Flatten[ Table[ DivisorSigma[k-n, n], {k, 1, rows}, {n, k, 1, -1}]] (* From Jean-François Alcover, Nov 15 2011 *)
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CROSSREFS
| Rows: A000005, A000203, A001157, A001158, A001159, A001160, A013954-A013972; columns: A000051, A034472, A001576, A034474, A034488, A034491, A034496, A034513, A034517, A034524, A034660; row sums A108639; diagonals A082245, A023887; also see A082771, A109976, A109977, A109978.
Sequence in context: A080786 A036838 A066010 * A026820 A091438 A011794
Adjacent sequences: A109971 A109972 A109973 * A109975 A109976 A109977
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KEYWORD
| easy,nonn,tabl,nice
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Jul 06 2005
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