OFFSET
1,1
LINKS
Eric Weisstein's World of Mathematics, Clique
Eric Weisstein's World of Mathematics, Menger Sponge Graph
Index entries for linear recurrences with constant coefficients, signature (29, -188, 160).
FORMULA
a(n) = 3*20^n - 2*8^n + 1.
a(n) = 29*a(n-1) - 188*a(n-2) + 160*a(n-3).
G.f.: x*(-45 + 232*x - 320*x^2)/(-1 + 29*x - 188*x^2 + 160*x^3).
MATHEMATICA
Table[3 20^n - 2 8^n + 1, {n, 20}]
LinearRecurrence[{29, -188, 160}, {45, 1073, 22977}, 20]
CoefficientList[Series[(-45 + 232 x - 320 x^2)/(-1 + 29 x - 188 x^2 + 160 x^3), {x, 0, 20}], x]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Eric W. Weisstein, Sep 11 2017
STATUS
approved