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Search: id:A109956
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| 1, -1, 1, 3, -4, 1, -12, 18, -7, 1, 55, -88, 42, -10, 1, -273, 455, -245, 75, -13, 1, 1428, -2448, 1428, -510, 117, -16, 1, -7752, 13566, -8379, 3325, -910, 168, -19, 1, 43263, -76912, 49588, -21252, 6578, -1472, 228, -22, 1, -246675, 444015, -296010, 134550, -45630, 11700, -2223, 297, -25, 1, 1430715, -2601300
(list; table; graph; listen)
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OFFSET
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0,4
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COMMENT
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Riordan array (g,f) where f/(1-f)^3=x and g=1-f. First column is (-1)^n*C(3n,n)/(2n+1), a signed version of A001764. Second column is a signed version of A006629. Diagonal sums are A109957.
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FORMULA
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Number triangle T(n, k)=(-1)^(n-k)*((3k+1)/(2n+k+1))*binomial(3n, n-k)
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EXAMPLE
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Rows begin
1,
-1,1;
3,-4,1;
-12,18,-7,1;
55,-88,42,-10,1;
-273,455,-245,75,-13,1;
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CROSSREFS
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Sequence in context: A147721 A114608 A154602 this_sequence A123319 A076785 A110506
Adjacent sequences: A109953 A109954 A109955 this_sequence A109957 A109958 A109959
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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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