A239455 Number of Look-and-Say partitions of n; see Comments.
0, 1, 2, 2, 4, 5, 7, 10, 13, 16, 21, 28, 33, 45, 55, 65, 83, 105, 121, 155, 180, 217, 259, 318, 362, 445, 512, 614, 707, 850, 958, 1155, 1309, 1543, 1754, 2079, 2327, 2740, 3085, 3592, 4042, 4699, 5253, 6093, 6815, 7839, 8751, 10069, 11208, 12832, 14266, 16270
Offset: 0
Keywords
Examples
The 11 partitions of 6 generate 7 Look-and-Say partitions as follows: 6 -> 111111 51 -> 111111 42 -> 111111 411 -> 21111 33 -> 222 321 -> 111111 3111 -> 3111 222 -> 33 2211 -> 222 21111 -> 411 111111 -> 6, so that a(6) counts these 7 partitions: 111111, 21111, 222, 3111, 33, 411, 6.
Crossrefs
These partitions are listed by A239454 in graded reverse-lex order.
The non-Wilf case is counted by A351592.
A181819 = Heinz number of the prime signature of n (prime shadow).
A279790 counts disjoint families on strongly normal multisets.
A329738 = compositions with all equal run-lengths.
Counting words with all distinct run-lengths:
Programs
-
Mathematica
LS[part_List] := Reverse[Sort[Flatten[Map[Table[#[[2]], {#[[1]]}] &, Tally[part]]]]]; LS[n_Integer] := #[[Reverse[Ordering[PadRight[#]]]]] &[DeleteDuplicates[Map[LS, IntegerPartitions[n]]]]; TableForm[t = Map[LS[#] &, Range[10]]](*A239454,array*) Flatten[t](*A239454,sequence*) Map[Length[LS[#]] &, Range[25]](*A239455*) (* Peter J. C. Moses, Mar 18 2014 *) disjointFamilies[y_]:=Select[Tuples[IntegerPartitions/@Length/@Split[y]],UnsameQ@@Join@@#&]; Table[Length[Select[IntegerPartitions[n],Length[disjointFamilies[#]]>0&]],{n,0,10}] (* Gus Wiseman, Aug 11 2025 *)
Comments