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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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0
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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
(list; table; graph; refs; listen; history; internal format)
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OFFSET
| 0,14
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FORMULA
| G.f.: Sum(Product(1-1/(1+((1+x)^i-1)*y),i=1..n),n=0..infinity).
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EXAMPLE
| 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
| Cf. (row sums)A138265, (column sums)A005321, A135589.
Sequence in context: A127560 A098172 A049759 * A036875 A036877 A049763
Adjacent sequences: A137249 A137250 A137251 * A137253 A137254 A137255
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KEYWORD
| nonn,tabl
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AUTHOR
| Vladeta Jovovic (vladeta(AT)eunet.rs), Mar 11 2008
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