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Search: id:A124395
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| A124395 |
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Expansion of (1-2x)/(1-2x+2x^3). |
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+0
3
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| 1, 0, 0, -2, -4, -8, -12, -16, -16, -8, 16, 64, 144, 256, 384, 480, 448, 128, -704, -2304, -4864, -8320, -12032, -14336, -12032, 0, 28672, 81408, 162816, 268288, 373760, 421888, 307200, -133120, -1110016, -2834432
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OFFSET
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0,4
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COMMENT
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Diagonal sums of number array A124394.
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FORMULA
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a(n)=sum{k=0..floor(n/2), sum{j=0..k+1, C(k+1,j)C(n-j+1,2k+1)(-2)^j}};
a(n) = term (2,2) in the 3x3 matrix [2,1,0; 0,0,1; -2,0,0]^n. [From Alois P. Heinz (heinz(AT)hs-heilbronn.de), Sep 10 2008]
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MAPLE
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a:= n-> (Matrix([[2, 1, 0], [0, 0, 1], [ -2, 0, 0]])^n)[2, 2]: seq (a(n), n=0..35); [From Alois P. Heinz (heinz(AT)hs-heilbronn.de), Sep 10 2008]
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CROSSREFS
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Sequence in context: A160162 A064711 A050865 this_sequence A024908 A019442 A048166
Adjacent sequences: A124392 A124393 A124394 this_sequence A124396 A124397 A124398
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KEYWORD
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easy,sign
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Oct 30 2006
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