A352521 - OEIS

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A352521

Triangle read by rows where T(n,k) is the number of integer compositions of n with k strong nonexcedances (parts below the diagonal).

1, 1, 0, 1, 1, 0, 2, 1, 1, 0, 3, 2, 2, 1, 0, 4, 5, 3, 3, 1, 0, 6, 8, 7, 6, 4, 1, 0, 9, 12, 15, 12, 10, 5, 1, 0, 13, 19, 27, 25, 22, 15, 6, 1, 0, 18, 32, 43, 51, 46, 37, 21, 7, 1, 0, 25, 51, 70, 94, 94, 83, 58, 28, 8, 1, 0, 35, 77, 117, 162, 184, 176, 141, 86, 36, 9, 1, 0

(list; table; graph; refs; listen; history; text; internal format)

OFFSET

0,7

LINKS

Andrew Howroyd, Table of n, a(n) for n = 0..1325

MathOverflow, Why 'excedances' of permutations? [closed].

EXAMPLE

Triangle begins:

1 0

1 1 0

2 1 1 0

3 2 2 1 0

4 5 3 3 1 0

6 8 7 6 4 1 0

9 12 15 12 10 5 1 0

13 19 27 25 22 15 6 1 0

18 32 43 51 46 37 21 7 1 0

25 51 70 94 94 83 58 28 8 1 0

For example, row n = 6 counts the following compositions (empty column indicated by dot):

(6) (51) (312) (1113) (11112) (111111) .

(15) (114) (411) (1122) (11121)

(24) (132) (1131) (2112) (11211)

(33) (141) (1212) (2121) (21111)

(42) (213) (1221) (3111)

(123) (222) (1311) (12111)

(231) (2211)

(321)

MATHEMATICA

pa[y_]:=Length[Select[Range[Length[y]], #>y[[#]]&]];

Table[Length[Select[Join@@Permutations/@IntegerPartitions[n], pa[#]==k&]], {n, 0, 15}, {k, 0, n}]

PROG

(PARI) T(n)={my(v=vector(n+1, i, i==1), r=v); for(k=1, n, v=vector(#v, j, sum(i=1, j-1, if(k>i, x, 1)*v[j-i])); r+=v); vector(#v, i, Vecrev(r[i], i))}

{ my(A=T(10)); for(i=1, #A, print(A[i])) } \\ Andrew Howroyd, Jan 19 2023

CROSSREFS

Row sums are A011782.

The version for partitions is A114088.

Row sums without the last term are A131577.

The version for permutations is A173018.

Column k = 0 is A219282.

The corresponding rank statistic is A352514.

The weak version is A352522, first column A238874, rank statistic A352515.

The opposite version is A352524, first column A008930, rank stat A352516.

The weak opposite version is A352525, first col A177510, rank stat A352517.

A008292 is the triangle of Eulerian numbers (version without zeros).

A238349 counts comps by fixed points, first col A238351, rank stat A352512.

A352490 is the strong nonexcedance set of A122111.

A352523 counts comps by nonfixed points, first A352520, rank stat A352513.

Cf. A088218, A115994, A238352, A350839, A352487, A352491.

Sequence in context: A235501 A116382 A050606 * A277721 A023416 A080791

Adjacent sequences: A352518 A352519 A352520 * A352522 A352523 A352524

KEYWORD

nonn,tabl

AUTHOR

Gus Wiseman, Mar 22 2022

EXTENSIONS

Terms a(66) and beyond from Andrew Howroyd, Jan 19 2023

STATUS

approved