A367218 Number of integer partitions of n whose length can be written as a nonnegative linear combination of the distinct parts.

1, 1, 1, 2, 4, 6, 8, 13, 18, 26, 35, 50, 66, 92, 119, 160, 208, 275, 350, 457, 579, 742, 933, 1185, 1476, 1859, 2300, 2868, 3531, 4371, 5343, 6575, 8003, 9776, 11842, 14394, 17351, 20987, 25191, 30315, 36257, 43448, 51753, 61776, 73342, 87192, 103184, 122253, 144211

Offset: 0

Author

Gus Wiseman, Nov 14 2023

Keywords

• nonn

Comments

The Heinz numbers of these partitions are given by A367226.

Examples

			The partition (4,2,1) has 3 = (2)+(1) or 3 = (1+1+1) so is counted under a(7).
The a(1) = 1 through a(7) = 13 partitions:
  (1)  (11)  (21)   (22)    (32)     (42)      (52)
             (111)  (31)    (41)     (51)      (61)
                    (211)   (221)    (321)     (322)
                    (1111)  (311)    (411)     (331)
                            (2111)   (2211)    (421)
                            (11111)  (3111)    (511)
                                     (21111)   (2221)
                                     (111111)  (3211)
                                               (4111)
                                               (22111)
                                               (31111)
                                               (211111)
                                               (1111111)
		

Crossrefs

The following sequences count and rank integer partitions and finite sets according to whether their length is a subset-sum or linear combination of the parts. The current sequence is starred.

sum-full sum-free comb-full comb-free

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partitions: A367212 A367213 A367218* A367219

strict: A367214 A367215 A367220 A367221

subsets: A367216 A367217 A367222 A367223

ranks: A367224 A367225 A367226 A367227

A000041 counts integer partitions, strict A000009.

A002865 counts partitions whose length is a part, complement A229816.

A008284 counts partitions by length, strict A008289.

A240855 counts strict partitions whose length is a part, complement A240861.

A365046 counts combination-full subsets, differences of A364914.

Cf. A088314, A363225, A364350, A365073, A365311, A365918.

Programs

Mathematica

combs[n_,y_]:=With[{s=Table[{k,i},{k,y}, {i,0,Floor[n/k]}]}, Select[Tuples[s], Total[Times@@@#]==n&]];
Table[Length[Select[IntegerPartitions[n], combs[Length[#], Union[#]]!={}&]], {n,0,15}]

Extensions

a(31)-a(48) from Chai Wah Wu, Nov 15 2023