OFFSET
1,1
LINKS
Colin Barker, Table of n, a(n) for n = 1..1000
Eric Weisstein's World of Mathematics, Sun Graph
Eric Weisstein's World of Mathematics, Vertex-Induced Subgraph
Index entries for linear recurrences with constant coefficients, signature (5,-5,-1,2).
FORMULA
a(n) = A206776(n) + n - 1.
From Colin Barker, May 25 2017: (Start)
G.f.: x*(3 - x - 8*x^2 + 2*x^3)/((1 - x)^2*(1 - 3*x - 2*x^2)).
a(n) = -1 + n + ((3-sqrt(17))/2)^n + ((3+sqrt(17))/2)^n.
a(n) = 5*a(n-1) - 5*a(n-2) - a(n-3) + 2*a(n-4) for n>4. (End)
MATHEMATICA
LinearRecurrence[{5, -5, -1, 2}, {3, 14, 47, 164}, 20]
PROG
(PARI) Vec(x*(3 - x - 8*x^2 + 2*x^3) / ((1 - x)^2*(1 - 3*x - 2*x^2)) + O(x^40)) \\ Colin Barker, May 25 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Eric W. Weisstein, May 24 2017
STATUS
approved