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A137252
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Triangle T(n,k) read by rows: number of k X k triangular (0,1)-matrices with exactly n entries equal to 1 and no zero rows or columns.
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4
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1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 4, 1, 0, 0, 0, 4, 11, 1, 0, 0, 0, 1, 33, 26, 1, 0, 0, 0, 0, 42, 171, 57, 1, 0, 0, 0, 0, 26, 507, 718, 120, 1, 0, 0, 0, 0, 8, 840, 4017, 2682, 247, 1, 0, 0, 0, 0, 1, 865, 12866, 25531, 9327, 502, 1, 0, 0, 0, 0, 0, 584, 26831, 138080, 141904, 30973, 1013, 1
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OFFSET
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0,14
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LINKS
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FORMULA
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G.f.: Sum(Product(1-1/(1+((1+x)^i-1)*y), i=1..n), n=0..infinity).
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EXAMPLE
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Triangle T(n,k) begins:
1;
0, 1;
0, 0, 1;
0, 0, 1, 1;
0, 0, 0, 4, 1;
0, 0, 0, 4, 11, 1;
0, 0, 0, 1, 33, 26, 1;
0, 0, 0, 0, 42, 171, 57, 1;
0, 0, 0, 0, 26, 507, 718, 120, 1;
...
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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