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 A091055 Expansion of x*(1-2*x)/((1-x)*(1+2*x)*(1-6*x)). 3
 0, 1, 3, 23, 127, 783, 4655, 28015, 167919, 1007855, 6046447, 36280047, 217677551, 1306070767, 7836413679, 47018503919, 282110979823, 1692665966319, 10155995623151, 60935974088431, 365615843831535, 2193695064387311 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Number of walks of length n between adjacent vertices of the Johnson graph J(5,2). 6^n = A091054(n) + 6*a(n) + 3*4*A091056(n). LINKS G. C. Greubel, Table of n, a(n) for n = 0..1000 Eric Weisstein's World of Mathematics, Johnson Graph Index entries for linear recurrences with constant coefficients, signature (5,8,-12). FORMULA a(n) = (3*6^n - 5*(-2)^n + 2)/30. E.g.f.: (3*exp(6*x) - 5*exp(-2*x) + 2*exp(x))/30. - G. C. Greubel, Dec 27 2019 MAPLE seq( (3*6^n -5*(-2)^n +2)/30, n=0..30); # G. C. Greubel, Dec 27 2019 MATHEMATICA Table[(3*6^n -5*(-2)^n +2)/30, {n, 0, 30}] (* G. C. Greubel, Dec 27 2019 *) PROG (PARI) vector(31, n, (3*6^(n-1) -5*(-2)^(n-1) +2)/30) \\ G. C. Greubel, Dec 27 2019 (MAGMA) [(3*6^n -5*(-2)^n +2)/30: n in [0..30]]; // G. C. Greubel, Dec 27 2019 (MAGMA) R:=PowerSeriesRing(Integers(), 25); [0] cat  Coefficients(R!( x*(1-2*x)/((1-x)*(1+2*x)*(1-6*x)))); // Marius A. Burtea, Dec 30 2019 (Sage) [(3*6^n -5*(-2)^n +2)/30 for n in (0..30)] # G. C. Greubel, Dec 27 2019 (GAP) List([0..30], n-> (3*6^n -5*(-2)^n +2)/30); # G. C. Greubel, Dec 27 2019 CROSSREFS Cf. A091054, A091056. Sequence in context: A267656 A122883 A196424 * A154648 A031970 A196881 Adjacent sequences:  A091052 A091053 A091054 * A091056 A091057 A091058 KEYWORD easy,nonn AUTHOR Paul Barry, Dec 17 2003 STATUS approved

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Last modified June 26 05:16 EDT 2022. Contains 354877 sequences. (Running on oeis4.)