OFFSET
1,4
COMMENTS
a(n) is the number of finite multisets of positive integers summing to n such that every distinct submultiset has a different sum, and also every distinct submultiset has a different product.
LINKS
R. Ehrenborg and M. Readdy, The Mobius function of partitions with restricted block sizes, Advances in Applied Mathematics, Volume 39, Issue 3, September 2007, Pages 283-292.
EXAMPLE
The a(12) = 13 partitions are:
(12),
(10 2), (9 3), (8 4), (7 5), (6 6),
(8 2 2), (7 3 2), (5 5 2), (5 4 3), (4 4 4),
(3 3 3 3),
(2 2 2 2 2 2).
MATHEMATICA
nn=22;
dubQ[y_]:=And[UnsameQ@@Times@@@Union[Rest@Subsets[y]], UnsameQ@@Plus@@@Union[Rest@Subsets[y]]];
Table[Length@Select[IntegerPartitions[n], dubQ], {n, nn}]
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Gus Wiseman, Oct 23 2017
STATUS
approved