OFFSET
1,2
LINKS
R. H. Hardin, Table of n, a(n) for n=1..83
FORMULA
Empirical: a(n) = (n^4 + 8*n^3 + 11*n^2 - 32*n + 12)/12.
From G. C. Greubel, May 26 2016: (Start)
Empirical G.f.: x^2*(x^3 - x^2 - 4*x + 6)/(1-x)^5.
Empirical E.g.f.: (1/12)*(12 - 12*x + 42*x^2 + 14*x^3 + x^4)*exp(x) - 1. (End)
EXAMPLE
All solutions for n=3
...1.2...1.2...1.2...1.2...1.2...1.2...1.2...1.2...1.2...1.2...1.2...1.1...1.1
...2.2...2.2...2.2...1.2...1.2...1.2...1.3...1.3...3.2...3.2...3.3...2.2...2.2
...2.3...3.2...3.3...1.3...3.2...3.3...1.3...3.3...3.2...3.3...3.3...2.3...3.3
------
...1.1...1.1...1.1...1.1...1.1...1.1...1.1...1.1...1.3...1.3...1.3...1.3...1.3
...2.3...2.3...1.2...1.2...1.2...1.1...1.3...1.3...2.2...2.3...2.3...1.3...1.3
...2.3...3.3...1.3...3.2...3.3...2.3...2.2...2.3...2.2...2.3...3.3...2.2...2.3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 21 2009
STATUS
approved