A371731 Heinz numbers of non-biquanimous integer partitions. Numbers without a divisor having the same sum of prime indices as the quotient.

2, 3, 5, 6, 7, 8, 10, 11, 13, 14, 15, 17, 18, 19, 20, 21, 22, 23, 24, 26, 27, 28, 29, 31, 32, 33, 34, 35, 37, 38, 39, 41, 42, 43, 44, 45, 46, 47, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 65, 66, 67, 68, 69, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80

Offset

1,1

Comments

These partitions are counted by A371795, even case A006827.

The Heinz number of a partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k). This gives a bijective correspondence between positive integers and integer partitions.

A prime index of n is a number m such that prime(m) divides n. The multiset of prime indices of n is row n of A112798.

A finite multiset of numbers is defined to be biquanimous iff it can be partitioned into two multisets with equal sums. Biquanimous partitions are counted by A002219 aerated and ranked by A357976.

Links

Table of n, a(n) for n=1..66.

Formula

Numbers n without a divisor d|n such that A056239(d) = A056239(n/d).

Example

The prime indices of 975 are {2,3,3,6}, which are not biquanimous, so 975 is in the sequence.
The prime indices of 900 are {1,1,2,2,3,3}, which can be partitioned into {{1,2,3},{1,2,3}} or {{3,3},{1,1,2,2}}, so 900 is not in the sequence.

Mathematica

prix[n_]:=If[n==1, {}, Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]];
biqQ[y_]:=MemberQ[Total/@Subsets[y], Total[y]/2];
Select[Range[100], Not@*biqQ@*prix]

Crossrefs

The complement is A357976, counted by A002219.

For prime signature instead of indices we have A371782, complement A371781.

Partitions of this type are counted by A371795, even case A006827.

A108917 counts knapsack partitions, ranks A299702, strict A275972.

A112798 lists prime indices, reverse A296150, length A001222, sum A056239.

A237258 aerated counts biquanimous strict partitions, ranks A357854.

A321142 and A371794 count non-biquanimous strict partitions.

A321451 counts non-quanimous partitions, ranks A321453.

A321452 counts quanimous partitions, ranks A321454.

A366754 counts non-knapsack partitions, ranks A299729, strict A316402.

A371737 counts quanimous strict partitions, complement A371736.

A371783 counts k-quanimous partitions.

A371789 counts non-quanimous sets, differences A371790.

A371791 counts biquanimous sets, differences A232466.

A371792 counts non-biquanimous sets, differences A371793.

A371796 counts quanimous sets, differences A371797.

Cf. A000005, A002221, A027187, A035470, A064914, A299701, A300061, A318434, A321455, A326534, A357879, A366320, A367094.

Sequence in context: A047587 A285420 A028737 * A109423 A028801 A348751

Adjacent sequences: A371728 A371729 A371730 * A371732 A371733 A371734

Keyword

nonn

Author

Gus Wiseman, Apr 07 2024

Status

approved