A026793 Juxtaposed partitions of 1,2,3,... into distinct parts, ordered by number of terms and then lexicographically.

1, 2, 3, 1, 2, 4, 1, 3, 5, 1, 4, 2, 3, 6, 1, 5, 2, 4, 1, 2, 3, 7, 1, 6, 2, 5, 3, 4, 1, 2, 4, 8, 1, 7, 2, 6, 3, 5, 1, 2, 5, 1, 3, 4, 9, 1, 8, 2, 7, 3, 6, 4, 5, 1, 2, 6, 1, 3, 5, 2, 3, 4, 10, 1, 9, 2, 8, 3, 7, 4, 6, 1, 2, 7, 1, 3, 6, 1, 4, 5, 2, 3, 5, 1, 2, 3, 4, 11, 1, 10, 2, 9, 3, 8, 4, 7, 5, 6, 1, 2, 8, 1, 3, 7, 1, 4, 6, 2, 3, 6, 2, 4

Offset

1,2

Comments

This is the Abramowitz and Stegun ordering. - Franklin T. Adams-Watters, Apr 28 2006

Links

Alois P. Heinz, Rows n = 1..32, flattened

M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy].

Example

The partitions of 5 into distinct parts are [5], [1,4] and [2,3], so row 5 is 5,1,4,2,3.
Triangle begins:
[1];
[2];
[3], [1,2];
[4], [1,3];
[5], [1,4], [2,3];
[6], [1,5], [2,4], [1,2,3];
[7], [1,6], [2,5], [3,4], [1,2,4];
[8], [1,7], [2,6], [3,5], [1,2,5], [1,3,4];
[9], [1,8], [2,7], [3,6], [4,5], [1,2,6], [1,3,5], [2,3,4];

Maple

b:= proc(n, i) b(n, i):= `if`(n=0, [[]], `if`(i>n, [],
      [map(x->[i, x[]], b(n-i, i+1))[], b(n, i+1)[]]))
    end:
T:= n-> map(x-> x[], sort(b(n, 1)))[]:
seq(T(n), n=1..12);  # Alois P. Heinz, Jun 22 2020

Mathematica

Array[SortBy[Map[Reverse, Select[IntegerPartitions[#], UnsameQ @@ # &]], Length] &, 12] // Flatten (* Michael De Vlieger, Jun 22 2020 *)
b[n_, i_] := b[n, i] = If[n == 0, {{}}, If[i>n, {}, Join[Prepend[#, i]& /@ b[n-i, i+1], b[n, i+1]]]];
T[n_] := Sort[b[n, 1]];
Array[T, 12] // Flatten (* Jean-François Alcover, Jun 09 2021, after Alois P. Heinz *)

Crossrefs

Cf. A118457, A118458 (partition lengths), A015723 (total row lengths), A036036, A000009, A246688.

Sequence in context: A097293 A296656 A303945 * A344089 A329631 A239304

Adjacent sequences: A026790 A026791 A026792 * A026794 A026795 A026796

Keyword

nonn,tabf

Author

Clark Kimberling

Extensions

Incorrect program removed by Georg Fischer, Jun 22 2020

Status

approved