A108244 Triangle read by rows: row n gives list of all compositions of n ordered first by decreasing length, then by reverse colexicographical order.

1, 1, 1, 2, 1, 1, 1, 1, 2, 2, 1, 3, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 2, 1, 1, 1, 3, 2, 2, 3, 1, 4, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 1, 1, 1, 3, 1, 2, 2, 2, 1, 2, 1, 3, 1, 2, 2, 1, 3, 1, 1, 1, 4, 2, 3, 3, 2, 4, 1, 5, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1

Offset: 1

Author

Hugo van der Sanden, Jun 20 2005

Keywords

• nonn
• tabf

Comments

An example of a sequence which contains all finite sequences of positive integers as subsequences.

From Andrey Zabolotskiy, May 18 2018: (Start)

At first, the ordering within the compositions of fixed length coincides with the lexicographical order (which is the case of A228369), but for n = 5 the partitions {2, 1, 2}, {1, 3, 1}, {2, 2, 1} go in this order because the order becomes reverse lexicographical when they are reversed (read right-to-left): {2, 1, 2}, {1, 3, 1}, {1, 2, 2}.

Length of k-th composition is A124748(k-1)+1.

Reversing every composition gives A296772. (End)

Examples

			The first 5 rows are:
{1}
{1, 1}, {2}
{1, 1, 1}, {1, 2}, {2, 1}, {3}
{1, 1, 1, 1}, {1, 1, 2}, {1, 2, 1}, {2, 1, 1}, {1, 3}, {2, 2}, {3, 1}, {4}
{1, 1, 1, 1, 1}, {1, 1, 1, 2}, {1, 1, 2, 1}, {1, 2, 1, 1}, {2, 1, 1, 1}, {1, 1, 3}, {1, 2, 2}, {2, 1, 2}, {1, 3, 1}, {2, 2, 1}, {3, 1, 1}, {1, 4}, {2, 3}, {3, 2}, {4, 1}, {5}
		

Links

• Eric Weisstein's World of Mathematics, Combinatorial composition

Crossrefs

Cf. A045623, A124748.

Triangles of compositions: A066099 (main entry for compositions; similar to the Mathematica ordering for partitions, A080577), A124734 (similar to the Abramowitz & Stegun ordering for partitions, A036036), and this sequence (similar to the Maple partition ordering, A080576), A296772.

Programs

Mathematica

Flatten[ Table[ Reverse[ # ] & /@ Reverse[ Sort[ Flatten[ Permutations[ # ] & /@ Partitions[ n], 1]]], {n, 6}]] (* Robert G. Wilson v, Jun 22 2005 *)

Extensions

More terms from Robert G. Wilson v, Jun 22 2005

Name corrected by Andrey Zabolotskiy, May 18 2018