OFFSET
0,3
COMMENTS
Related to a tiling of the plane by heptagons.
LINKS
Colin Barker, Table of n, a(n) for n = 0..1000
Peter Steinbach, Golden fields: a case for the heptagon, Math. Mag. Vol. 70, No. 1, Feb. 1997, 22-31.
Index entries for linear recurrences with constant coefficients, signature (0,8,0,-9).
FORMULA
a(n) = 8*a(n-2) - 9*a(n-4). - Colin Barker, Jan 05 2018
a(2*n)/a(2*n-1) ~ 2*a(2*n+1)/a(2*n) ~ 1 + sqrt(7). - Kyle MacLean Smith, Oct 11 2019
PROG
(PARI) concat(0, Vec((x + 3*x^2 - 2*x^3 - 3*x^4)/(1 - 8*x^2 + 9*x^4) + O(x^40))) \\ Colin Barker, Jan 05 2018
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Jan 04 2018, following a suggestion from Roger L. Bagula
STATUS
approved