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Number of maximal irredundant sets in the n-wheel graph.
1

%I #14 Aug 21 2017 13:10:26

%S 1,3,4,7,11,12,15,15,31,63,67,100,144,213,344,479,698,993,1502,2247,

%T 3252,4777,6970,10284,15211,22298,32728,47985,70645,103962,152707,

%U 224383,329509,484452,712275,1046737,1538165,2260110,3321933,4882575,7175739

%N Number of maximal irredundant sets in the n-wheel graph.

%C The wheel graph is well defined for n >= 4. Sequence extended to n=2 using formula. - _Andrew Howroyd_, Aug 19 2017

%H Colin Barker, <a href="/A291063/b291063.txt">Table of n, a(n) for n = 2..1000</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/MaximalIrredundantSet.html">Maximal Irredundant Set</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/WheelGraph.html">Wheel Graph</a>

%H <a href="/index/Rec#order_15">Index entries for linear recurrences with constant coefficients</a>, signature (1,1,0,0,0,-1,-1,-1,1,3,-1,-1,0,-1,1).

%F a(n) = A286954(n-1) + 1. - _Andrew Howroyd_, Aug 19 2017

%F G.f.: x^2*(1 + 2*x - 6*x^5 - 7*x^6 - 8*x^7 + 9*x^8 + 30*x^9 - 11*x^10 - 12*x^11 - 14*x^13 + 15*x^14) / ((1 - x)*(1 - x^2 - x^3 - x^4 - x^5 + x^7 + 2*x^8 + x^9 - 2*x^10 - x^11 + x^14)). - _Colin Barker_, Aug 20 2017

%t Table[1 + RootSum[1 - #^3 - 2 #^4 + #^5 + 2 #^6 + #^7 - #^9 - #^10 - #^11 - #^12 + #^14 &, #^(n - 1) &], {n, 2, 20}]

%t 1 + RootSum[1 - #^3 - 2 #^4 + #^5 + 2 #^6 + #^7 - #^9 - #^10 - #^11 - #^12 + #^14 &, #^Range[20] &]

%t LinearRecurrence[{1, 1, 0, 0, 0, -1, -1, -1, 1, 3, -1, -1, 0, -1, 1}, {1, 3, 4, 7, 11, 12, 15, 15, 31, 63, 67, 100, 144, 213, 344}, 20]

%t CoefficientList[

%t Series[(1 + 2 x - 6 x^5 - 7 x^6 - 8 x^7 + 9 x^8 + 30 x^9 - 11 x^10 - 12 x^11 - 14 x^13 + 15 x^14)/((1 - x) (1 - x^2 - x^3 - x^4 - x^5 + x^7 + 2 x^8 + x^9 - 2 x^10 - x^11 + x^14)), {x, 0, 20}], x]

%o (PARI) Vec(x^2*(1 + 2*x - 6*x^5 - 7*x^6 - 8*x^7 + 9*x^8 + 30*x^9 - 11*x^10 - 12*x^11 - 14*x^13 + 15*x^14) / ((1 - x)*(1 - x^2 - x^3 - x^4 - x^5 + x^7 + 2*x^8 + x^9 - 2*x^10 - x^11 + x^14)) + O(x^60)) \\ _Colin Barker_, Aug 20 2017

%Y Cf. A286954, A290494.

%K nonn

%O 2,2

%A _Eric W. Weisstein_, Aug 17 2017

%E a(2)-a(3) and a(21)-a(42) from _Andrew Howroyd_, Aug 19 2017