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A095364
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Number of walks of length n between two adjacent nodes in the cycle graph C_9.
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0
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1, 0, 3, 0, 10, 0, 35, 1, 126, 11, 462, 78, 1716, 455, 6435, 2380, 24311, 11628, 92398, 54264, 352947, 245157, 1354102, 1081575, 5215250, 4686826, 20156580, 20030039, 78152535, 84672780, 303906051, 354822776, 1184959314, 1476390160
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| In general 2^n/m*Sum(r,0,m-1,Cos(2Pi*k*r/m)Cos(2Pi*r/m)^n) is the number of walks of length n between two nodes at distance k in the cycle graph C_m. Here we have m=9 and k=1.
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FORMULA
| a(n)= 2^n/9*Sum(r, 0, 8, Cos(2Pi*r/9)^(n+1)) G.f.: x(-1+x+2x^2-x^3)/((1+x)(-1+2x)(1-3x^2+x^3)) a(n)=a(n-1)+5a(n-2)-4a(n-3)-5a(n-4)+2a(n-5)
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CROSSREFS
| Sequence in context: A094472 A028850 A138364 * A094052 A161678 A081658
Adjacent sequences: A095361 A095362 A095363 * A095365 A095366 A095367
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KEYWORD
| nonn
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AUTHOR
| Herbert Kociemba (kociemba(AT)t-online.de), Jul 03 2004
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