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A370174
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Triangle read by rows: Riordan array (1/(1 - x), x*(1 + x)/(1 - x - x^2)).
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7
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1, 1, 1, 1, 3, 1, 1, 6, 5, 1, 1, 11, 15, 7, 1, 1, 19, 37, 28, 9, 1, 1, 32, 82, 87, 45, 11, 1, 1, 53, 170, 234, 169, 66, 13, 1, 1, 87, 337, 573, 535, 291, 91, 15, 1, 1, 142, 647, 1314, 1511, 1061, 461, 120, 17, 1, 1, 231, 1213, 2871, 3933, 3398, 1904, 687, 153, 19, 1
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OFFSET
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0,5
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LINKS
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FORMULA
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T(n,k) = T(n-1,k) + T(n-1,k-1) + T(n-2,k) + T(n-2,k-1), T(n,0) = 1, T(n,k) = 0 if k > n.
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EXAMPLE
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Triangle T(n,k) begins:
k=0 1 2 3 4 5 6
n=0: 1;
n=1: 1, 1;
n=2: 1, 3, 1;
n=3: 1, 6, 5, 1;
n=4: 1, 11, 15, 7, 1;
n=5: 1, 19, 37, 28, 9, 1;
n=6: 1, 32, 82, 87, 45, 11, 1;
...
87 = 28 + 37 + 7 + 15.
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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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