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A147721
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a(n) = C(2,n) DELTA C(0,n).
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5
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1, 1, 1, 3, 4, 1, 11, 17, 7, 1, 41, 72, 40, 10, 1, 153, 301, 208, 72, 13, 1, 571, 1244, 1021, 446, 113, 16, 1, 2131, 5093, 4819, 2525, 813, 163, 19, 1, 7953, 20688, 22104, 13452, 5218, 1336, 222, 22, 1, 29681, 83481, 99192, 68568, 30986, 9586, 2042, 290, 25, 1
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OFFSET
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0,4
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COMMENTS
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Triangle T equal to [1,2,1,0,0,0,...] DELTA [1,0,0,0,...] for Deléham DELTA as in A084938.
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LINKS
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FORMULA
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Riordan array ((1-3x)/(1-4x+x^2), x(1-x)/(1-4x+x^2)).
T(n,k) = 4*T(n-1,k) + T(n-1,k-1) - T(n-2,k) - T(n-2,k-1), n > 1. - Philippe Deléham, Feb 13 2012
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EXAMPLE
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Triangle begins
1;
1, 1;
3, 4, 1;
11, 17, 7, 1;
41, 72, 40, 10, 1;
153, 301, 208, 72, 13, 1;
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MATHEMATICA
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nmax=9; Flatten[CoefficientList[Series[CoefficientList[Series[(1 - 3*x)/(1 - 4*x + (1 + y)*x^2 - y*x), {x, 0, nmax}], x], {y, 0, nmax}], y]] (* Indranil Ghosh, Mar 10 2017, after Philippe Deléham *)
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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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