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A051160
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Coefficients in expansion of (1-x)^floor(n/2)(1+x)^ceiling(n/2).
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9
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1, 1, 1, 1, 0, -1, 1, 1, -1, -1, 1, 0, -2, 0, 1, 1, 1, -2, -2, 1, 1, 1, 0, -3, 0, 3, 0, -1, 1, 1, -3, -3, 3, 3, -1, -1, 1, 0, -4, 0, 6, 0, -4, 0, 1, 1, 1, -4, -4, 6, 6, -4, -4, 1, 1, 1, 0, -5, 0, 10, 0, -10, 0, 5, 0, -1, 1, 1, -5, -5, 10, 10, -10, -10, 5, 5, -1, -1, 1, 0, -6, 0, 15, 0, -20
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OFFSET
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0,13
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COMMENTS
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Triangle T(n,k), 0<=k<=n, read by rows given by: [1,0,-1,0,0,0,0,0,...]DELTA[1,-2,1,0,0,0,0,0,...] where DELTA is the operator defined in A084938. - Philippe Deléham, Sep 22 2008
The production matrix for this array has bivariate e.g.f. equal to exp(-t*x)*(1-t). - Paul Barry, Nov 22 2008
The elements of the matrix inverse are apparently T^(-1)(n,k) = (-1)^(n+k)*T(n,k). - R. J. Mathar, Apr 08 2013
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LINKS
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FORMULA
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T(n, k) = -T(n-2, k-2) + T(n-2, k). T(0, 0) = T(1, 0) = T(1, 1) = 1.
T(n,k) = T(n-1,k) + (-1)^(n-1)*T(n-1,k-1), T(0,0)=1. - Jose Ramon Real, Nov 10 2007
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EXAMPLE
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Triangle begins:
1;
1, 1;
1, 0, -1;
1, 1, -1, -1;
1, 0, -2, 0, 1;
1, 1, -2, -2, 1, 1;
...
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MAPLE
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(1-x)^floor(n/2)*(1+x)^ceil(n/2) ;
coeftayl(%, x=0, k) ;
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MATHEMATICA
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t[n_, k_] := Coefficient[(1-x)^Floor[n/2]*(1+x)^Ceiling[n/2], x, k]; Table[t[n, k], {n, 0, 12}, {k, 0, n}] // Flatten (* Jean-François Alcover, Jan 09 2014 *)
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PROG
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(PARI) {T(n, k) = polcoeff( (1 - x)^(n\2) * (1 + x)^ceil(n/2), k)}
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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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