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A261781
Number T(n,k) of compositions of n where each part i is marked with a word of length i over a k-ary alphabet whose letters appear in alphabetical order and all k letters occur at least once in the composition; triangle T(n,k), n >= 0, 0 <= k <= n, read by rows.
17
1, 0, 1, 0, 2, 3, 0, 4, 16, 13, 0, 8, 66, 132, 75, 0, 16, 248, 924, 1232, 541, 0, 32, 892, 5546, 13064, 13060, 4683, 0, 64, 3136, 30720, 114032, 195020, 155928, 47293, 0, 128, 10888, 162396, 893490, 2327960, 3116220, 2075948, 545835
OFFSET
0,5
COMMENTS
From Vaclav Kotesovec, Oct 14 2017: (Start)
Conjecture: For k > 0 the recurrence order for column k is equal to k*(k+1)/2.
Column k > 0 is asymptotic to c(k) * d(k)^n, where c(k) and d(k) are constants (dependent only on k).
k c(k) d(k)
1 A131577(n) ~ 0.50000000000000000000000000 * 2.00000000000000000000000000^n.
2 A293579(n) ~ 0.60355339059327376220042218 * 3.41421356237309504880168872^n.
3 A293580(n) ~ 0.64122035031051210658648604 * 4.84732210186307263951891624^n.
4 A293581(n) ~ 0.66065168848540565019767995 * 6.28521350788324520158143964^n.
5 A293582(n) ~ 0.67250239588725756267924287 * 7.72502395887257562679242875^n.
6 A293583(n) ~ 0.68048292906885160660288253 * 9.16579514882621927923459043^n.
7 A293584(n) ~ 0.68622254929933439577377124 * 10.6071156901906815408327973^n.
8 A293585(n) ~ 0.69054873168854973836384871 * 12.0487797070167958138215794^n.
9 A293586(n) ~ 0.69392626461456654033893782 * 13.4906727630621977261008808^n.
10 A293587(n) ~ 0.69663630864564830007443110 * 14.9327261729129660014886221^n.
---
Conjecture: d(k+1) - d(k) tends to 1/log(2).
d(2) - d(1) = 1.414213562373095048801688724209698...
d(3) - d(2) = 1.433108539489977590717227522340838...
d(4) - d(3) = 1.437891406020172562062523400686067...
d(5) - d(4) = 1.439810450989330425210989107036901...
d(6) - d(5) = 1.440771189953643652442161677346934...
d(7) - d(6) = 1.441320541364462261598206961226199...
d(8) - d(7) = 1.441664016826114272988782079622148...
d(9) - d(8) = 1.441893056045401912279301345910755...
d(10)- d(9) = 1.442053409850768275387741352145193...
1 / log(2) = 1.442695040888963407359924681001892...
(End)
LINKS
E. Munarini, M. Poneti, S. Rimaldi, Matrix compositions, JIS 12 (2009) 09.4.8, Table 2.
FORMULA
T(n,k) = Sum_{i=0..k} (-1)^i * C(k,i) * A261780(n,k-i).
EXAMPLE
A(3,2) = 16: 3aab, 3abb, 2aa1b, 2ab1a, 2ab1b, 2bb1a, 1a2ab, 1a2bb, 1b2aa, 1b2ab, 1a1a1b, 1a1b1a, 1a1b1b, 1b1a1a, 1b1a1b, 1b1b1a.
Triangle T(n,k) begins:
1;
0, 1;
0, 2, 3;
0, 4, 16, 13;
0, 8, 66, 132, 75;
0, 16, 248, 924, 1232, 541;
0, 32, 892, 5546, 13064, 13060, 4683;
0, 64, 3136, 30720, 114032, 195020, 155928, 47293;
...
MAPLE
A:= proc(n, k) option remember; `if`(n=0, 1,
add(A(n-j, k)*binomial(j+k-1, k-1), j=1..n))
end:
T:= (n, k)-> add(A(n, k-i)*(-1)^i*binomial(k, i), i=0..k):
seq(seq(T(n, k), k=0..n), n=0..10);
MATHEMATICA
A[n_, k_] := A[n, k] = If[n==0, 1,
Sum[A[n-j, k]*Binomial[j+k-1, k-1], {j, 1, n}]];
T[n_, k_] := Sum[A[n, k-i]*(-1)^i*Binomial[k, i], {i, 0, k}];
Table[T[n, k], {n, 0, 10}, {k, 0, n}] // Flatten (* Jean-François Alcover, Feb 08 2017, translated from Maple *)
CROSSREFS
Row sums give A120733.
Main diagonal gives A000670.
T(2n,n) gives A261784.
T(n+1,n)/2 gives A083385.
Cf. A261719 (same for partitions), A261780.
Sequence in context: A258818 A261275 A140326 * A211402 A256064 A126436
KEYWORD
nonn,tabl
AUTHOR
Alois P. Heinz, Aug 31 2015
STATUS
approved