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Search: id:A109970
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| A109970 |
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Riordan array (1,x(1-x)^2). |
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+0
4
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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; listen)
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OFFSET
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0,5
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COMMENT
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Row sums are A077954. Diagonal sums are (-1)^n*A094686(n). Matrix inverse is A109971.
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FORMULA
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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
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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
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Sequence in context: A003992 A118345 A118350 this_sequence A116088 A136501 A128307
Adjacent sequences: A109967 A109968 A109969 this_sequence A109971 A109972 A109973
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KEYWORD
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easy,sign,tabl
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Jul 06 2005
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