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A110608
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Number triangle T(n,k) = binomial(n,k)*binomial(2n,n-k).
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6
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1, 2, 1, 6, 8, 1, 20, 45, 18, 1, 70, 224, 168, 32, 1, 252, 1050, 1200, 450, 50, 1, 924, 4752, 7425, 4400, 990, 72, 1, 3432, 21021, 42042, 35035, 12740, 1911, 98, 1, 12870, 91520, 224224, 244608, 127400, 31360, 3360, 128, 1, 48620, 393822, 1145664, 1559376
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OFFSET
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0,2
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COMMENTS
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LINKS
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FORMULA
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n-th row polynomial R(n,t) = [x^n] ( (1 + t*x)*(1 + x)^2 )^n.
Cf. A008459, whose n-th row polynomial is equal to [x^n] ( (1 + t*x)*(1 + x) )^n.
exp( Sum_{n >= 1} R(n,t)*x^n/n ) = 1 + (2 + t)*x + (5 + 6*t + t^2)*x^2 + ... is the o.g.f. for A120986. (End)
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EXAMPLE
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Triangle begin
n\k| 0 1 2 3 4 5
---------------------------------
0 | 1
1 | 2 1
2 | 6 8 1
3 | 20 45 18 1
4 | 70 224 168 32 1
5 | 252 1050 1200 450 50 1
...
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MATHEMATICA
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Flatten[Table[Table[Binomial[n, k]Binomial[2n, n-k], {k, 0, n}], {n, 0, 10}]] (* Harvey P. Dale, Aug 10 2011 *)
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PROG
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(PARI) for(n=0, 10, for(k=0, n, print1(binomial(n, k)*binomial(2*n, n-k), ", "))) \\ G. C. Greubel, Sep 01 2017
(Maxima)
B(x, y):=(sqrt(-x*(4*x^2*y^3+(-12*x^2-8*x)*y^2+(12*x^2-20*x+4)*y-4*x^2+x))/(2*3^(3/2))-(x*(18*y+9)-2)/54)^(1/3);
C(x, y):=-B(x, y)-(x*(3*y-3)+1)/(9*B(x, y))-1/3;
A(x, y):=x*diff(C(x, y), x)*(-1/C(x, y)+1/(1+C(x, y)));
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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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