login
A366320
Irregular triangle read by rows where T(n,k) is the number of subsets of {1..n} without a subset summing to k.
20
1, 2, 2, 3, 4, 4, 3, 6, 6, 7, 8, 8, 6, 6, 9, 11, 11, 14, 14, 15, 16, 16, 12, 12, 9, 17, 17, 20, 20, 24, 27, 27, 30, 30, 31, 32, 32, 24, 24, 18, 17, 26, 31, 29, 35, 36, 43, 47, 50, 51, 56, 59, 59, 62, 62, 63
OFFSET
1,2
EXAMPLE
Triangle begins:
1
2 2 3
4 4 3 6 6 7
8 8 6 6 9 11 11 14 14 15
16 16 12 12 9 17 17 20 20 24 27 27 30 30 31
32 32 24 24 18 17 26 31 29 35 36 43 47 50 51 56 59 59 62 62 63
Row n = 3 counts the following subsets:
{} {} {} {} {} {}
{2} {1} {1} {1} {1} {1}
{3} {3} {2} {2} {2} {2}
{2,3} {1,3} {3} {3} {3}
{1,2} {1,2} {1,2}
{2,3} {1,3} {1,3}
{2,3}
MATHEMATICA
Table[Length[Select[Subsets[Range[n]], FreeQ[Total/@Subsets[#], k]&]], {n, 8}, {k, n*(n+1)/2}]
CROSSREFS
Row lengths are A000217.
The diagonal T(n,n) is A365377, complement A365376.
The complement is counted by A365381.
A000009 counts subsets summing to n.
A000124 counts distinct possible sums of subsets of {1..n}.
A124506 counts combination-free subsets, differences of A326083.
A365046 counts combination-full subsets, differences of A364914.
Sequence in context: A086416 A168148 A147968 * A065167 A332298 A300404
KEYWORD
nonn,tabf
AUTHOR
Gus Wiseman, Oct 12 2023
STATUS
approved