OFFSET
0,5
LINKS
Joerg Arndt and N. J. A. Sloane, Counting Words that are in "Standard Order"
FORMULA
Conjectures from Colin Barker, Nov 25 2017: (Start)
G.f.: x^2*(1 - 9*x + 34*x^2 - 71*x^3 + 100*x^4 - 97*x^5 + 52*x^6 - 12*x^7) / ((1 - x)^3*(1 - 2*x)^2*(1 - 3*x)).
a(n) = (2*(3+3^n) - 3*(2+2^n)*n + 6*n^2) / 12 for n>3.
a(n) = 10*a(n-1) - 40*a(n-2) + 82*a(n-3) - 91*a(n-4) + 52*a(n-5) - 12*a(n-6) for n>9.
(End)
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Dec 06 2016
STATUS
approved