OFFSET
0,2
COMMENTS
Number of (s(0), s(1), ..., s(2n)) such that 0 < s(i) < 10 and |s(i) - s(i-1)| = 1 for i = 1,2,...,2n, s(0) = 3, s(2n) = 3. - Herbert Kociemba, Jun 16 2004
LINKS
Michael De Vlieger, Table of n, a(n) for n = 0..1791
N. J. A. Sloane, Transforms
FORMULA
G.f.: (x^4-7*x^3+11*x^2-6*x+1)/((1-3*x+x^2)*(1-5*x+5*x^2)).
a(n) = (1/5)*Sum_{r=1..9} sin(3*r*Pi/10)^2*(2*cos(r*Pi/10))^(2*n), n >= 1. - Herbert Kociemba, Jun 16 2004
MATHEMATICA
CoefficientList[Series[(x^4 - 7 x^3 + 11 x^2 - 6 x + 1)/((1 - 3 x + x^2) (1 - 5 x + 5 x^2)), {x, 0, 23}], x] (* Michael De Vlieger, Feb 12 2022 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved