OFFSET
1,2
LINKS
Eric Weisstein's World of Mathematics, Graph Cycle
Eric Weisstein's World of Mathematics, Sierpinski Tetrahedron Graph
Index entries for linear recurrences with constant coefficients, signature (4).
FORMULA
a(n) = 219*4^(n - 2) for n > 2.
a(n) = 4*a(n-1) for n > 2.
G.f.: -2*x^2*(109 + 2*x)/(-1 + 4*x).
MATHEMATICA
Table[Piecewise[{{0, n == 1}, {218, n == 2}}, 219 4^(n - 2)], {n, 20}]
Join[{0, 218}, LinearRecurrence[{4}, {876}, 20]]
CoefficientList[Series[-2 x (109 + 2 x)/(-1 + 4 x), {x, 0, 20}], x]
PROG
(PARI) concat(0, Vec(-2*x^2*(109 + 2*x)/(-1 + 4*x) + O(x^50))) \\ Michel Marcus, Sep 19 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Eric W. Weisstein, Sep 18 2017
STATUS
approved