|
|
A300383
|
|
In the ranked poset of integer partitions ordered by refinement, a(n) is the size of the lower ideal generated by the partition with Heinz number n.
|
|
26
|
|
|
1, 1, 2, 1, 3, 2, 5, 1, 3, 3, 7, 2, 11, 5, 5, 1, 15, 3, 22, 3, 8, 7, 30, 2, 6, 11, 4, 5, 42, 5, 56, 1, 11, 15, 11, 3, 77, 22, 17, 3, 101, 8, 135, 7, 7, 30, 176, 2, 14, 6, 23, 11, 231, 4, 15, 5, 33, 42, 297, 5, 385, 56, 11, 1, 23, 11, 490, 15, 45, 11, 627, 3
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,3
|
|
COMMENTS
|
The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k). The size of the corresponding upper ideal is A317141(n). Chains are A213427(n) and maximal chains are A002846(n).
|
|
LINKS
|
|
|
FORMULA
|
a(x * y) <= a(x) * a(y).
|
|
EXAMPLE
|
The a(30) = 5 partitions are (321), (2211), (3111), (21111), (111111), with corresponding Heinz numbers: 30, 36, 40, 48, 64.
|
|
MATHEMATICA
|
primeMS[n_]:=If[n===1, {}, Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]];
Table[Length[Union[Sort/@Join@@@Tuples[IntegerPartitions/@primeMS[n]]]], {n, 50}]
|
|
CROSSREFS
|
Cf. A000041, A001055, A001222, A002846, A056239, A112798, A213427, A215366, A265947, A296150, A299200, A299202, A299925, A300273.
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|