A375127 - OEIS

A375127

The anti-run-leader transformation for standard compositions.

0, 1, 2, 3, 4, 2, 1, 7, 8, 4, 10, 5, 1, 1, 3, 15, 16, 8, 4, 9, 2, 10, 2, 11, 1, 1, 6, 3, 3, 3, 7, 31, 32, 16, 8, 17, 36, 4, 4, 19, 2, 2, 42, 21, 2, 2, 5, 23, 1, 1, 1, 3, 1, 6, 1, 7, 3, 3, 14, 7, 7, 7, 15, 63, 64, 32, 16, 33, 8, 8, 8, 35, 4, 36, 18, 9, 4, 4, 9

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OFFSET

0,3

COMMENTS

The a(n)-th composition in standard order lists the leaders of anti-runs of the n-th composition in standard order.

The leaders of anti-runs in a sequence are obtained by splitting it into maximal consecutive anti-runs (sequences with no adjacent equal terms) and taking the first term of each.

The k-th composition in standard order (graded reverse-lexicographic, A066099) is obtained by taking the set of positions of 1's in the reversed binary expansion of k, prepending 0, taking first differences, and reversing again. This gives a bijective correspondence between nonnegative integers and integer compositions.

Does this sequence contain all nonnegative integers?

LINKS

Table of n, a(n) for n=0..78.

Gus Wiseman, Statistics, classes, and transformations of standard compositions.

Gus Wiseman, Sequences counting and ranking compositions by their leaders (for six types of runs).

FORMULA

A000120(a(n)) = A333381(n).

A065120(a(n)) = A065120(n).

A070939(a(n)) = A374516(n).

EXAMPLE

The 346th composition in standard order is (2,2,1,2,2), with anti-runs ((2),(2,1,2),(2)), with leaders (2,2,2). This is the 42nd composition in standard order, so a(346) = 42.

MATHEMATICA

stc[n_]:=Differences[Prepend[Join @@ Position[Reverse[IntegerDigits[n, 2]], 1], 0]]//Reverse;

stcinv[q_]:=Total[2^(Accumulate[Reverse[q]])]/2;

Table[stcinv[First/@Split[stc[n], UnsameQ]], {n, 0, 100}]

CROSSREFS

Positions of elements of A233564 are A374638, counted by A374518.

Positions of elements of A272919 are A374519, counted by A374517.

Ranks of rows of A374515.

A011782 counts compositions.

A238130, A238279, A333755 count compositions by number of runs.

All of the following pertain to compositions in standard order:

- Length is A000120.