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A087621
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(1,1) entry of powers of the orthogonal design shown below.
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2
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-1, 2, 4, -56, 80, -352, 64, 2176, -4864, 31232, -23552, -14336, 217088, -2056192, 2375680, -7307264, -4390912, 102367232, -169607168, 877133824, -397410304, -3042967552, 9265217536, -68308434944, 62495129600, -78483816448, -342993403904
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OFFSET
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1,2
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COMMENTS
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-1 +1 +1 -1 -1 +1 -1 -1
+1 +1 -1 -1 -1 -1 -1 +1
+1 +1 +1 +1 +1 +1 -1 +1
+1 -1 +1 -1 +1 -1 -1 -1
+1 -1 +1 -1 -1 +1 +1 +1
+1 +1 -1 -1 +1 +1 +1 -1
-1 +1 +1 -1 +1 -1 +1 +1
+1 +1 +1 +1 -1 -1 +1 -1
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REFERENCES
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S. Severini, A note on two integer sequences arising from the 3-dimensional hypercube, Technical Report, Department of Computer Science, University of Bristol, Bristol, UK (October 2003).
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LINKS
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FORMULA
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a(0)=1, a(1)=-1, a(2)=2, a(3)=4, a(n) = 4*a(n-2) - 64*a(n-4). - T. D. Noe, Dec 11 2006
G.f.: -x*(4*x+1)*(16*x^2-6*x+1)/(64*x^4-4*x^2+1). - Colin Barker, Aug 10 2012
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CROSSREFS
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KEYWORD
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easy,sign
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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