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 A287498 Number of maximal independent vertex sets (and minimal vertex covers) in the n-web graph. 0
 0, 4, 9, 12, 30, 55, 105, 212, 405, 794, 1551, 3015, 5889, 11477, 22374, 43636, 85068, 165871, 323418, 630582, 1229517, 2397289, 4674198, 9113711, 17769780, 34647305, 67554891, 131717661, 256821477, 500747300 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Eric Weisstein's World of Mathematics, Maximal Independent Vertex Set Eric Weisstein's World of Mathematics, Minimal Vertex Cover Eric Weisstein's World of Mathematics, Web Graph Index entries for linear recurrences with constant coefficients, signature (0,2,3,1). FORMULA G.f.: x^2*(-4 - 9*x - 4*x^2)/(-1 + 2*x^2 + 3*x^3 + x^4). a(n) = 2*a(n-2) + 3*a(n-3) + a(n-4). MATHEMATICA Table[RootSum[-1 - 3 # - 2 #^2 + #^4 &, #^n &], {n, 20}] LinearRecurrence[{0, 2, 3, 1}, {0, 4, 9, 12}, 20] CROSSREFS Sequence in context: A179808 A083351 A055381 * A174911 A032820 A197615 Adjacent sequences:  A287495 A287496 A287497 * A287499 A287500 A287501 KEYWORD nonn,easy AUTHOR Eric W. Weisstein, May 25 2017 STATUS approved

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Last modified December 6 16:24 EST 2019. Contains 329808 sequences. (Running on oeis4.)