A302655 Number of minimal total dominating sets in the n-path graph.
0, 1, 2, 1, 2, 4, 3, 4, 8, 9, 10, 16, 21, 25, 36, 49, 60, 81, 112, 144, 189, 256, 336, 441, 592, 784, 1029, 1369, 1820, 2401, 3182, 4225, 5586, 7396, 9815, 12996, 17200, 22801, 30210, 40000, 53001, 70225, 93000, 123201, 163240, 216225, 286416, 379456, 502665
Offset: 1
Links
- Andrew Howroyd, Table of n, a(n) for n = 1..200
- Eric Weisstein's World of Mathematics, Minimal Total Dominating Set.
- Eric Weisstein's World of Mathematics, Path Graph.
- Index entries for linear recurrences with constant coefficients, signature (0,0,1,1,1,1,0,-1,-1).
Programs
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Mathematica
Table[If[Mod[n, 2] == 0, (RootSum[-1 - # + #^3 &, #^(n/2 + 5) (5 - 6 # + 4 #^2) &]/23)^2, (RootSum[-1 + # - 2 #^2 + #^3 &, #^((n - 1)/2) (4 - 2 # + 5 #^2) &] + RootSum[-1 + #^2 + #^3 &, #^((n - 1)/2) (-5 + 6 # + 3 #^2) &])/23], {n, 50}] LinearRecurrence[{0, 0, 1, 1, 1, 1, 0, -1, -1}, {0, 1, 2, 1, 2, 4, 3, 4, 8}, 50] CoefficientList[Series[(x (1 + 2 x + x^2 + x^3 + x^4 - x^5 - 2 x^6 - x^7))/(1 - x^3 - x^4 - x^5 - x^6 + x^8 + x^9), {x, 0, 50}], x]
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PARI
concat([0],Vec(x^2*(1 + 2*x + x^2 + x^3 + x^4 - x^5 - 2*x^6 - x^7)/(1 - x^3 - x^4 - x^5 - x^6 + x^8 + x^9) + O(x^50))) \\ Andrew Howroyd, Apr 15 2018
Formula
From Andrew Howroyd, Apr 15 2018: (Start)
a(n) = a(n-3) + a(n-4) + a(n-5) + a(n-6) - a(n-8) - a(n-9) for n > 9.
G.f.: x^2*(1 + 2*x + x^2 + x^3 + x^4 - x^5 - 2*x^6 - x^7)/(1 - x^3 - x^4 - x^5 - x^6 + x^8 + x^9).
a(2*n) = A000931(n+5)^2. (End)
Extensions
Terms a(20) and beyond from Andrew Howroyd, Apr 15 2018
Comments