The number of unordered partitions of n into k parts is equal to the sum of the unordered partitions of n-k into i parts, 1<=i<=k. e.g. P(9,4) is based on P(5,1-4), i.e. 5 41 32 311 221 2111 Adding a [1,1,1,1] mask gives P(9,5); 6111 5211 4311 4221 3321 3222 Jon Perry perry@globalnet.co.uk http://www.users.globalnet.co.uk/~perry/maths/ http://www.users.globalnet.co.uk/~perry/DIVMenu/ BrainBench MVP for HTML and JavaScript http://www.brainbench.com