OFFSET
1,4
COMMENTS
A rooted partition of n is an integer partition of n - 1.
EXAMPLE
The a(8) = 10 rooted twice-partitions:
(6), (51), (42), (321),
(5)(), (41)(), (32)(), (4)(1), (3)(2),
(3)(1)().
MATHEMATICA
twirtns[n_]:=Join@@Table[Tuples[IntegerPartitions[#-1]&/@ptn], {ptn, IntegerPartitions[n-1]}];
Table[Select[twirtns[n], And[UnsameQ@@Total/@#, UnsameQ@@Join@@#]&]//Length, {n, 20}]
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Gus Wiseman, Mar 26 2018
STATUS
approved