OFFSET
1,5
REFERENCES
H.S.M. Coxeter and W.O.J. Moser, Generators and Relations for Discrete Groups, Fourth Edition, (p.134).
FORMULA
Conjecture: a(n) = 9*a(n-1) - 26*a(n-2) + 25*a(n-3) - 4*a(n-4).
Empirical g.f.: x^4 / ((1 - 4*x)*(1 - 5*x + 6*x^2 - x^3)). - Colin Barker, Feb 24 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Jamaine Paddyfoot and John W. Layman, Jul 24 2002
STATUS
approved