A326534 - OEIS

A326534

MM-numbers of multiset partitions where every part has the same sum.

1, 2, 3, 4, 5, 7, 8, 9, 11, 13, 16, 17, 19, 23, 25, 27, 29, 31, 32, 35, 37, 41, 43, 47, 49, 53, 59, 61, 64, 67, 71, 73, 79, 81, 83, 89, 97, 101, 103, 107, 109, 113, 121, 125, 127, 128, 131, 137, 139, 143, 149, 151, 157, 163, 167, 169, 173, 175, 179, 181, 191

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OFFSET

1,2

COMMENTS

First differs from A298538 in lacking 187.

These are numbers where each prime index has the same sum of prime indices. 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. The multiset multisystem with MM-number n is obtained by taking the multiset of prime indices of each prime index of n. For example, the prime indices of 78 are {1,2,6}, so the multiset multisystem with MM-number 78 is {{},{1},{1,2}}.

LINKS

Table of n, a(n) for n=1..61.

Gus Wiseman, Sequences counting and ranking multiset partitions whose part lengths, sums, or averages are constant or strict.

EXAMPLE

The sequence of multiset partitions where every part has the same sum, preceded by their MM-numbers, begins:

1: {}

2: {{}}

3: {{1}}

4: {{},{}}

5: {{2}}

7: {{1,1}}

8: {{},{},{}}

9: {{1},{1}}

11: {{3}}

13: {{1,2}}

16: {{},{},{},{}}

17: {{4}}

19: {{1,1,1}}

23: {{2,2}}

25: {{2},{2}}

27: {{1},{1},{1}}

29: {{1,3}}

31: {{5}}

32: {{},{},{},{},{}}

35: {{2},{1,1}}

MATHEMATICA

primeMS[n_]:=If[n==1, {}, Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]];

Select[Range[100], SameQ@@Total/@primeMS/@primeMS[#]&]

CROSSREFS

Cf. A035470, A038041, A112798, A302242, A320324, A321455, A326518, A326533, A326535, A326536, A326537.

Sequence in context: A326837 A326847 A298538 * A046686 A137944 A359390

Adjacent sequences: A326531 A326532 A326533 * A326535 A326536 A326537

KEYWORD

nonn

AUTHOR

Gus Wiseman, Jul 12 2019

STATUS

approved