OFFSET
0,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
J. W. Cannon, P. Wagreich, Growth functions of surface groups, Mathematische Annalen, 1992, Volume 293, pp. 239-257. See Prop. 3.1.
Index entries for linear recurrences with constant coefficients, signature (1, 0, 1, -1, 1, 0, 1, -1).
FORMULA
G.f.: (x^2+1)*(x^4+1)*(x+1)^2/(x^8-x^7-x^5+x^4-x^3-x+1).
MATHEMATICA
CoefficientList[Series[(x^2 + 1)*(x^4 + 1)*(x + 1)^2/(x^8 - x^7 - x^5 + x^4 - x^3 - x + 1), {x, 0, 50}], x] (* G. C. Greubel, Aug 07 2017 *)
LinearRecurrence[{1, 0, 1, -1, 1, 0, 1, -1}, {1, 3, 5, 8, 12, 17, 25, 37, 53}, 50] (* Harvey P. Dale, Jul 26 2024 *)
PROG
(PARI) Vec((x^2+1)*(x^4+1)*(x+1)^2/(x^8-x^7-x^5+x^4-x^3-x+1) + O(x^100)) \\ Altug Alkan, Dec 29 2015
CROSSREFS
Coordination sequences for triangular tilings of hyperbolic space: A001630, A007283, A054886, A078042, A096231, A163876, A179070, A265057, A265058, A265059, A265060, A265061, A265062, A265063, A265064, A265065, A265066, A265067, A265068, A265069, A265070, A265071, A265072, A265073, A265074, A265075, A265076, A265077.
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Dec 29 2015
STATUS
approved