OFFSET
0,2
LINKS
Muniru A Asiru, Table of n, a(n) for n = 0..1000
R. Bacher and P. Flajolet, Pseudo-factorials, Elliptic Functions and Continued Fractions, arXiv:0901.1379 [math.CA], 2009.
FORMULA
From Chai Wah Wu, Nov 30 2018: (Start)
a(n) = a(n-2) + a(n-3) - a(n-5) - a(n-6) + a(n-8) for n > 7 (conjectured).
G.f.: (-8*x^7 - 4*x^6 + 3*x^5 + 8*x^4 + 7*x^3 - 6*x^2 - 8*x - 1)/((x - 1)*(x + 1)*(x^6 - x^3 + 1)) (conjectured). (End)
MAPLE
a:= proc(n) option remember; `if`(n=0, 1, (-1)^n*add(binomial(n-1, k)*a(k)*a(n-1-k), k=0..n-1)) end: seq(modp(a(n), 9), n=0..100); # Muniru A Asiru, Jul 29 2018
MATHEMATICA
b[0] = 1;
b[n_] := b[n] = (-1)^n Sum[Binomial[n-1, k] b[k] b[n-k-1], {k, 0, n-1}];
a[n_] := Mod[b[n], 9]; Table[a[n], {n, 0, 100}] (* Jean-François Alcover, Jul 29 2018 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Feb 08 2009
STATUS
approved