OFFSET
4,1
LINKS
Index entries for linear recurrences with constant coefficients, signature (6,-12,10,-12,24,-16).
FORMULA
G.f.: 2*x^4*(x - 1)^2/(1-2*x^3)/(1-2*x)^3 = (x^3/(1-2*x)^3-x^3/(1-2*x^3))/3
EXAMPLE
a(5) = 8 because 11122, 11212, 11123, 11132, 11213, 11312, 11133, 11313 are all ternary Lyndon words of length 5 with three 1's
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Mike Zabrocki, Nov 05 2006
STATUS
approved