Dear SeqFans, I need to part the sequence a,b,c,d...(of length L) in all, n, possible ways: a,b,c,d a,b,cd a,bc,d ab,c,d ab,cd a,bcd abc,d abcd in this case L=4 and n=8 (modulo my errs). My (humble) Qs: what is the function n(L) (guess that this is known one...) how to code this in Mathematica/PARI/Maple (in order of decreasing preference) thx, zak