A335126 A multiset whose multiplicities are the prime indices of n is inseparable.

3, 5, 7, 10, 11, 13, 14, 17, 19, 21, 22, 23, 26, 28, 29, 31, 33, 34, 37, 38, 39, 41, 43, 44, 46, 47, 51, 52, 53, 55, 57, 58, 59, 61, 62, 65, 66, 67, 68, 69, 71, 73, 74, 76, 78, 79, 82, 83, 85, 86, 87, 88, 89, 91, 92, 93, 94, 95, 97, 101, 102, 103, 104, 106

Offset

1,1

Comments

A multiset is separable if it has a permutation that is an anti-run, meaning there are no adjacent equal parts.

A multiset whose multiplicities are the prime indices of n (such as row n of A305936) is not the same as the multiset of prime indices of n. For example, the prime indices of 12 are {1,1,2}, while a multiset whose multiplicities are {1,1,2} is {1,1,2,3}.

Links

Table of n, a(n) for n=1..64.

Example

The sequence of terms together with the corresponding multisets begins:
   3: {1,1}
   5: {1,1,1}
   7: {1,1,1,1}
  10: {1,1,1,2}
  11: {1,1,1,1,1}
  13: {1,1,1,1,1,1}
  14: {1,1,1,1,2}
  17: {1,1,1,1,1,1,1}
  19: {1,1,1,1,1,1,1,1}
  21: {1,1,1,1,2,2}
  22: {1,1,1,1,1,2}
  23: {1,1,1,1,1,1,1,1,1}
  26: {1,1,1,1,1,1,2}
  28: {1,1,1,1,2,3}
  29: {1,1,1,1,1,1,1,1,1,1}

Mathematica

nrmptn[n_]:=Join@@MapIndexed[Table[#2[[1]], {#1}]&, If[n==1, {}, Flatten[Cases[FactorInteger[n]//Reverse, {p_, k_}:>Table[PrimePi[p], {k}]]]]];
Select[Range[100], Select[Permutations[nrmptn[#]], !MatchQ[#, {___, x_, x_, ___}]&]=={}&]

Crossrefs

The complement is A335127.

Anti-run compositions are A003242.

Anti-runs are ranked by A333489.

Separable partitions are A325534.

Inseparable partitions are A325535.

Separable factorizations are A335434.

Inseparable factorizations are A333487.

Separable partitions are ranked by A335433.

Inseparable partitions are ranked by A335448.

Anti-run permutations of prime indices are A335452.

Patterns contiguously matched by compositions are A335457.

Cf. A025487, A056239, A106351, A112798, A114938, A181819, A181821, A278990, A292884, A335407, A335489, A335516, A335838.

Sequence in context: A071561 A241561 A241008 * A367225 A173708 A239929

Adjacent sequences: A335123 A335124 A335125 * A335127 A335128 A335129

Keyword

nonn

Author

Gus Wiseman, Jul 01 2020

Status

approved