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 A098657 Expansion of (1-x-4x^2)/((1-2x)(1-8x^2)). 2
 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; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS 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. REFERENCES P. Feinsilver, J. Kocik, Krawtchouk matrices from classical and quantum walks, Contemporary Mathematics, 287 2001, pp. 83-96. LINKS Index entries for linear recurrences with constant coefficients, signature (2,8,-16). FORMULA a(n)=2^((3n-4)/2)(1+(-1)^n)+2^(n-1); a(n)=2a(n-1)+8a(n-2)-16a(n-3). CROSSREFS Cf. A098655, A098656. Sequence in context: A038258 A298776 A114330 * A126936 A333813 A327370 Adjacent sequences:  A098654 A098655 A098656 * A098658 A098659 A098660 KEYWORD easy,nonn AUTHOR Paul Barry, Sep 19 2004 STATUS approved

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Last modified June 20 12:49 EDT 2021. Contains 345164 sequences. (Running on oeis4.)