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A257556
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Triangle, read by rows, T(n,k)= Sum_{i=0..(n-k)/2} C(2*k,i)*C(n-2*i-1,k-1).
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0
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1, 1, 1, 3, 2, 1, 3, 7, 3, 1, 4, 12, 12, 4, 1, 4, 23, 28, 18, 5, 1, 4, 34, 66, 52, 25, 6, 1, 4, 49, 126, 143, 85, 33, 7, 1, 4, 64, 228, 328, 265, 128, 42, 8, 1, 4, 80, 372, 700, 701, 444, 182, 52, 9, 1, 4, 96, 573, 1352, 1705, 1320, 693, 248, 63
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OFFSET
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1,4
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LINKS
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FORMULA
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G.f.: (x-1)/((x^5+2*x^3+x)*y+x-1).
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EXAMPLE
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1;
1, 1;
3, 2, 1;
3, 7, 3, 1;
4, 12, 12, 4, 1;
4, 23, 28, 18, 5, 1;
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PROG
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(Maxima)
T(n, k):=sum(binomial(2*k, i)*binomial(n-2*i-1, k-1), i, 0, (n-k)/2);
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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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