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2, 2, 2, 2, 2, 2, 2, 3, 3, 2, 2, 4, 4, 4, 2, 2, 5, 6, 6, 5, 2, 2, 6, 9, 8, 9, 6, 2, 2, 7, 13, 12, 12, 13, 7, 2, 2, 8, 18, 19, 16, 19, 18, 8, 2, 2, 9, 24, 30, 24, 24, 30, 24, 9, 2, 2, 10, 31, 46, 39, 32, 39, 46, 31, 10, 2, 2, 11, 39, 68, 65, 48, 48, 65
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internal format)
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OFFSET
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0,1
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COMMENTS
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Row sums are twice Fibonacci numbers, A006355(n+2).
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LINKS
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FORMULA
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T(n,k) = 2 if k = 0 or k = n, A052509(n-1,k) + A052509(n-1,n-k) otherwise.
G.f.: Sum_{n>=0, 0<=k<=n} T(n,k) * x^n * y^k = (1-x^2*y) * (1/((1-x*y)*(1-x-x^2*y)) + 1/((1-x)*(1-x*y-x^2*y))). (End)
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EXAMPLE
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Rows:
2;
2,2;
2,2,2;
2,3,3,2;
...
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PROG
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(PARI) A052509(n, k) = sum(m=0, k, binomial(n-k, m));
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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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