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A207327
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Riordan array (1, x*(1+x)^2/(1-x)).
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0
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1, 0, 1, 0, 3, 1, 0, 4, 6, 1, 0, 4, 17, 9, 1, 0, 4, 32, 39, 12, 1, 0, 4, 48, 111, 70, 15, 1, 0, 4, 64, 240, 268, 110, 18, 1, 0, 4, 80, 432, 769, 530, 159, 21, 1, 0, 4, 96, 688, 1792, 1905, 924, 217, 24, 1, 0, 4
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OFFSET
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0,5
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COMMENTS
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Triangle T(n,k), read by rows, given by (0, 3, -5/3, 4/15, -3/5, 0, 0, 0, 0, 0, 0, 0, ...) DELTA (1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, ...) where DELTA is the operator defined in A084938.
Row sums are A077995(n).
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LINKS
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Table of n, a(n) for n=0..56.
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FORMULA
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T(2*n,n) = A119259(n).
G.f.: (1-x)/(1-(1+y)*x-2*y*x^2-y*x^3).
T(n,k) = T(n-1,k) + T(n-1,k-1) + 2*T(n-2,k-1) + T(n-3,k-1), T(0,0) = 1, T(1,0) = 0.
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EXAMPLE
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Triangle begins :
1
0, 1
0, 3, 1
0, 4, 6, 1
0, 4, 17, 9, 1
0, 4, 32, 39, 12, 1
0, 4, 48, 111, 70, 15, 1
0, 4, 64, 240, 268, 110, 18, 1
0, 4, 80, 432, 769, 530, 159, 21, 1
0, 4, 96, 688, 1792, 1905, 924, 217, 24, 1
0, 4, 112, 1008, 3584, 5503, 3999, 1477, 284, 27, 1
0, 4, 128, 1392, 6400, 13440, 13842, 7483, 2216, 360, 30, 1
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CROSSREFS
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Cf. Diagonals : A000012, A008585, A022266, A000007, A113311
Sequence in context: A212186 A274662 A186827 * A319083 A332099 A045406
Adjacent sequences: A207324 A207325 A207326 * A207328 A207329 A207330
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KEYWORD
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easy,nonn,tabl
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AUTHOR
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Philippe Deléham, Feb 17 2012
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STATUS
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approved
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