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A109970
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Riordan array (1,x(1-x)^2).
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3
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1, 0, 1, 0, -2, 1, 0, 1, -4, 1, 0, 0, 6, -6, 1, 0, 0, -4, 15, -8, 1, 0, 0, 1, -20, 28, -10, 1, 0, 0, 0, 15, -56, 45, -12, 1, 0, 0, 0, -6, 70, -120, 66, -14, 1, 0, 0, 0, 1, -56, 210, -220, 91, -16, 1, 0, 0, 0, 0, 28, -252, 495, -364, 120, -18, 1
(list; table; graph; refs; listen; history; internal format)
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OFFSET
| 0,5
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COMMENTS
| Row sums are A077954. Diagonal sums are (-1)^n*A094686(n). Matrix inverse is A109971.
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FORMULA
| G.f.: 1/(1-xy(1-x)^2); Number triangle T(n, k)=binomial(2k, n-k)*(-1)^(n-k).
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EXAMPLE
| Rows begin
1;
0,1;
0,-2,1;
0,1,-4,1;
0,0,6,-6,1;
0,0,-4,15,-8,1;
0,0,1,-20,28,-10,1;
0,0,0,15,-56,45,-12,1;
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CROSSREFS
| Sequence in context: A183135 A160114 * A116088 A136501 A180983 A128307
Adjacent sequences: A109967 A109968 A109969 * A109971 A109972 A109973
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KEYWORD
| easy,sign,tabl
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Jul 06 2005
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