OFFSET
4,2
COMMENTS
Also number of partitions of n objects of 2 colors into 4 parts, each part containing at least one black object.
REFERENCES
G. E. Andrews, The Theory of Partitions, Addison-Wesley, 1976 (Ch. XI, exercise 5 and Ch. XII, exercise 5).
FORMULA
G.f.: q^4*(q^12+q^10+2*q^9+4*q^8+2*q^7+4*q^6+2*q^5+4*q^4+2*q^3+q^2+1) / ((-1+q^4)^2*(-1+q^3)^2*(-1+q^2)^2*(-1+q)^2).
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Wouter Meeussen and Vladeta Jovovic, Dec 26 2003
EXTENSIONS
Edited and extended by Christian G. Bower, Jan 08 2004
STATUS
approved