A158609 Expansion of (1+8*x)/(1-x-81*x^2).

1, 9, 90, 819, 8109, 74448, 731277, 6761565, 65995002, 613681767, 5959276929, 55667500056, 538368931305, 5047436435841, 48655319871546, 457497671174667, 4398578580769893, 41455889945917920, 397740754988279253

Offset

0,2

References

H. S. M. Coxeter, Regular Polytopes, 3rd ed., Dover, NY, 1973, page 221.

Links

Table of n, a(n) for n=0..18.

Index entries for linear recurrences with constant coefficients, signature (1,81).

Formula

a(n) = a(n-1) + 81*a(n-2), a(0)=1, a(1)=9. - Philippe Deléham, Mar 26 2009

Mathematica

M = {{0, t}, {t, 1/t}};
v[0] = {1, 1};
v[n_] := v[n] = M.v[n - 1];
t = 3;
a = Table[t^n*v[n][[1]], {n, 0, 30}]

Crossrefs

Sequence in context: A052386 A246941 A186510 * A229250 A242161 A227713

Adjacent sequences: A158606 A158607 A158608 * A158610 A158611 A158612

Keyword

nonn,easy

Author

Roger L. Bagula, Mar 22 2009

Extensions

Clearer definition from Philippe Deléham, Mar 26 2009

Status

approved