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Search: id:A098657
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| A098657 |
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Expansion of (1-x-4x^2)/((1-2x)(1-8x^2)). |
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+0
3
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| 1, 1, 6, 4, 40, 16, 288, 64, 2176, 256, 16896, 1024, 133120, 4096, 1056768, 16384, 8421376, 65536, 67239936, 262144, 537395200, 1048576, 4297064448, 4194304, 34368126976, 16777216, 274911461376, 67108864, 2199157473280, 268435456
(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 1,1 element of A^n.
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REFERENCES
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P. Feinsilver, 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^((3n-4)/2)(1+(-1)^n)+2^(n-1); a(n)=2a(n-1)+8a(n-2)-16a(n-3).
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CROSSREFS
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Cf. A098655, A098656.
Sequence in context: A163939 A038258 A114330 this_sequence A112521 A109873 A014403
Adjacent sequences: A098654 A098655 A098656 this_sequence A098658 A098659 A098660
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KEYWORD
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easy,nonn
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Sep 19 2004
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