[seqfan] Partitioning the sequence (?)

[zak seidov]

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