OFFSET
1,12
EXAMPLE
Triangle begins:
1
1
1 1
1 1
1 1
1 1
1 4 1
1 3 7 1
1 9 1
1 1
1 43 35 1
1 102 62 1
1 1
1 68 595 1
1 17 187 871 1480 361 1
1 2650 657 1
Row 8 counts the following set partitions:
{{18}{27}{36}{45}} {{1236}{48}{57}} {{12348}{567}} {{12345678}}
{{138}{246}{57}} {{12357}{468}}
{{156}{237}{48}} {{12456}{378}}
{{1278}{3456}}
{{1368}{2457}}
{{1458}{2367}}
{{1467}{2358}}
MATHEMATICA
spsu[_, {}]:={{}}; spsu[foo_, set:{i_, ___}]:=Join@@Function[s, Prepend[#, s]&/@spsu[Select[foo, Complement[#, Complement[set, s]]=={}&], Complement[set, s]]]/@Cases[foo, {i, ___}];
Table[Length[spsu[Select[Subsets[Range[n]], Total[#]==d&], Range[n]]], {n, 12}, {d, Select[Divisors[n*(n+1)/2], #>=n&]}]
CROSSREFS
KEYWORD
nonn,tabf,more
AUTHOR
Gus Wiseman, Jan 08 2019
STATUS
approved