A371735 Maximal length of a set partition of the binary indices of n into blocks all having the same sum.

0, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 2, 1, 1, 2, 3, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 2, 1, 2, 1, 2, 1, 1, 2, 1, 1, 1, 1, 3, 2, 1, 2, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 1, 2, 1, 1, 2, 1

Offset

0,8

Comments

A binary index of n is any position of a 1 in its reversed binary expansion. The binary indices of n are row n of A048793.

If a(n) = k then the binary indices of n (row n of A048793) are k-quanimous (counted by A371783).

Links

Table of n, a(n) for n=0..86.

Example

The binary indices of 119 are {1,2,3,5,6,7}, and the set partitions into blocks with the same sum are:
  {{1,7},{2,6},{3,5}}
  {{1,5,6},{2,3,7}}
  {{1,2,3,6},{5,7}}
  {{1,2,3,5,6,7}}
So a(119) = 3.

Mathematica

sps[{}]:={{}}; sps[set:{i_, ___}]:=Join@@Function[s, Prepend[#, s]& /@ sps[Complement[set, s]]]/@Cases[Subsets[set], {i, ___}];
bix[n_]:=Join@@Position[Reverse[IntegerDigits[n, 2]], 1];
Table[Max[Length/@Select[sps[bix[n]], SameQ@@Total/@#&]], {n, 0, 100}]

Crossrefs

Set partitions of this type are counted by A035470, A336137.

A version for factorizations is A371733.

Positions of 1's are A371738.

Positions of terms > 1 are A371784.

A001055 counts factorizations.

A002219 (aerated) counts biquanimous partitions, ranks A357976.

A048793 lists binary indices, length A000120, reverse A272020, sum A029931.

A070939 gives length of binary expansion.

A321452 counts quanimous partitions, ranks A321454.

A326031 gives weight of the set-system with BII-number n.

A371783 counts k-quanimous partitions.

A371789 counts non-quanimous sets, differences A371790.

A371796 counts quanimous sets, differences A371797.

Cf. A006827, A038041, A096111, A279787, A305551, A321451, A321455, A322794, A326534, A371731, A371734.

Sequence in context: A058060 A338160 A336137 * A088323 A396866 A391426

Adjacent sequences: A371732 A371733 A371734 * A371736 A371737 A371738

Keyword

nonn

Author

Gus Wiseman, Apr 14 2024

Status

approved