OFFSET
1,1
COMMENTS
Extended to a(1)-a(2) using the recurrence.
LINKS
Eric Weisstein's World of Mathematics, Minimal Dominating Set
Eric Weisstein's World of Mathematics, Pan Graph
Index entries for linear recurrences with constant coefficients, signature (0, 1, 1, 1, 0, -1).
FORMULA
a(n) = a(n-2) + a(n-3) + a(n-4) - a(n-6).
G.f.: x*(2 + 2*x + x^2 + x^3 - 2*x^5)/(1 - x^2 - x^3 - x^4 + x^6).
MATHEMATICA
Table[-RootSum[1 - #^2 - #^3 - #^4 + #^6 &, -9 #^n + 33 #^(n + 1) - 23 #^(n + 2) - 45 #^(n + 3) - 38 #^(n + 4) + #^(n + 5) &]/229, {n, 20}]
LinearRecurrence[{0, 1, 1, 1, 0, -1}, {2, 2, 3, 5, 7, 8}, 50]
CoefficientList[Series[(2 + 2 x + x^2 + x^3 - 2 x^5)/(1 - x^2 - x^3 - x^4 + x^6), {x, 0, 20}], x]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Eric W. Weisstein, Jul 25 2017
STATUS
approved