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A035748
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Coordination sequence for C_11 lattice.
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3
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1, 242, 9922, 170610, 1690370, 11414898, 58227906, 240089586, 838478850, 2564399090, 7039035586, 17664712562, 41110086402, 89719625842, 185263467202, 364571790066, 687750033410, 1249849661170, 2197075886786, 3748850875506, 6227320558338, 10096197409650
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OFFSET
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0,2
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LINKS
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J. H. Conway and N. J. A. Sloane, Low-Dimensional Lattices VII: Coordination Sequences, Proc. Royal Soc. London, A453 (1997), 2369-2389 (pdf).
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FORMULA
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a(n) = [x^(2n)] ((1+x)/(1-x))^11.
G.f.: cosh(22*arctanh(sqrt(x))).
(-2*n^2-n)*a(n)+(4*n^2+8*n+246)*a(n+1)+(-2*n^2-7*n-6)*a(n+2)=0. (End)
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MAPLE
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f:= gfun:-rectoproc({(-2*n^2-n)*a(n)+(4*n^2+8*n+246)*a(n+1)+(-2*n^2-7*n-6)*a(n+2), a(0)=1, a(1)=242}, a(n), remember):
seq(f(n), n=0..100);
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MATHEMATICA
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RecurrenceTable[{(4*n^2 + 8*n + 246)*a[n+1] + (-2*n^2 - 7*n - 6)*a[n+2] + (-2*n^2 - n)*a[n] == 0, a[0] == 1, a[1] == 242}, a, {n, 0, 100}] (* Jean-François Alcover, Sep 16 2022, after Maple program *)
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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Joan Serra-Sagrista (jserra(AT)ccd.uab.es)
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EXTENSIONS
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STATUS
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approved
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