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Search: id:A098656
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| A098656 |
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Expansion of x(1-4x)/((1-2x)(1-8x^2)). |
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+0
3
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| 0, 1, -2, 4, -24, 16, -224, 64, -1920, 256, -15872, 1024, -129024, 4096, -1040384, 16384, -8355840, 65536, -66977792, 262144, -536346624, 1048576, -4292870144, 4194304, -34351349760, 16777216, -274844352512, 67108864, -2198889037824, 268435456, -17591649173504, 1073741824
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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Let A=[1,2,1;2,0,-2;1,-2,1] the 3 X 3 symmetric Krawtchouk matrix. Than a(n) is the 1,3 element of A^n.
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REFERENCES
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P. Feinsilver and J. Kocik, Krawtchouk matrices from classical and quantum walks, Contemporary Mathematics, 287 2001, pp. 83-96.
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FORMULA
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a(n)=2^(n-1)-2^(3(n-1)/2)(1+(-1)^n)/sqrt(2); a(n)=2a(n-1)+8a(n-2)-16a(n-3).
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CROSSREFS
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Cf. A098655, A098657.
Adjacent sequences: A098653 A098654 A098655 this_sequence A098657 A098658 A098659
Sequence in context: A009317 A081680 A090591 this_sequence A138611 A068506 A119036
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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), Sep 19 2004
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