OFFSET
0,1
COMMENTS
Extended to a(0)-a(1) using the formula/recurrence.
LINKS
Eric Weisstein's World of Mathematics, Crossed Prism Graph
Eric Weisstein's World of Mathematics, Independent Vertex Set
Eric Weisstein's World of Mathematics, Vertex Cover
Index entries for linear recurrences with constant coefficients, signature (12, -18, 4).
FORMULA
a(n) = 12*a(n-1) - 18*a(n-2) + 4*a(n-3).
G.f.: -3*x*(1 - 8*x + 6*x^2)/(-1 + 12*x - 18*x^2 + 4*x^3).
MATHEMATICA
RootSum[-4 + 18 # - 12 #^2 + #^3 &, #^Range[0, 20] &]
Table[RootSum[-4 + 18 # - 12 #^2 + #^3 &, #^n &], {n, 0, 20}]
LinearRecurrence[{12, -18, 4}, {12, 108, 1092}, {0, 20}]
CoefficientList[Series[-3 (1 - 8 x + 6 x^2)/(-1 + 12 x - 18 x^2 + 4 x^3), {x, 0, 20}], x]
CROSSREFS
KEYWORD
nonn
AUTHOR
Eric W. Weisstein, Sep 30 2017
STATUS
approved