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A282698 Irregular triangle read by rows: row n gives numbers of maximal chains of lengths n-1, n, n+1, ... in the Tamari lattice T_n. 4
1, 1, 1, 1, 1, 4, 2, 2, 1, 10, 22, 22, 18, 13, 12, 1, 20, 112, 232, 382, 348, 456, 390, 420, 334, 286, 1, 35, 392, 1744, 4474, 8435, 12732, 17337, 21158, 27853, 33940, 41230, 45048, 50752, 41826, 33592, 1, 56, 1092, 9220, 40414, 123704, 276324, 550932, 917884 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,6
COMMENTS
Nelson (2017) gives first nine columns of the transposed triangle.
LINKS
Luke Nelson, A recursion on maximal chains in the Tamari lattices, Discrete Mathematics 340.4 (2017): 661-677.
Luke Nelson, A recursion on maximal chains in the Tamari lattices, arXiv:1709.02987 [math.CO], (2017)
EXAMPLE
Triangle begins:
1;
1;
1, 1;
1, 4, 2, 2;
1, 10, 22, 22, 18, 13, 12;
1, 20, 112, 232, 382, 348, 456, 390, 420, 334, 286;
...
The transposed triangle, as given by Nelson, begins:
1, 1, 1, 1, 1, 1, 1, 1, 1, ...
1, 4, 10, 20, 35, 56, 84, ...
2, 22, 112, 392, 1092, 2604, ...
2, 22, 232, 1744, 9220, 37444, ...
18, 382, 4474, 40414, 280214, ...
13, 348, 8435, 123704, 1321879, ...
12, 456, 12732, 276324, 4578596, ...
390, 17337, 550932, 12512827, ...
420, 21158, 917884, 29499764, ...
334, 27853, 1510834, 62132126, ...
286, 33940, 2166460, 120837274, ...
41230, 3370312, 221484557, ...
45048, 4810150, 393364848, ...
50752, 7264302, 666955139, ...
41826, 10435954, 1134705692, ...
33592, 15227802, 1933708535, ...
...
MAPLE
s:= proc(n) s(n):=`if`(n=0, [], [s(n-1), []]) end:
f:= l-> l=[] or l[1]=[] and f(l[2]):
v:= proc(l) v(l):=`if`(f(l), [], [`if`(l[1]<>[],
[l[1][1], [l[1][2], l[2]]], [][]),
seq([w, l[2]], w=v(l[1])), seq([l[1], w], w=v(l[2]))])
end:
p:= proc(l) p(l):=`if`(f(l), 1, add(expand(x*p(w)), w=v(l))) end:
T:= n-> (h-> seq(coeff(h, x, i), i=ldegree(h)..degree(h)))(p(s(n))):
seq(T(n), n=1..8); # Alois P. Heinz, Jan 02 2018
CROSSREFS
Row sums give A027686.
Right border gives A003121(n-1).
Sequence in context: A071558 A179621 A350788 * A136709 A254969 A137239
KEYWORD
nonn,tabf
AUTHOR
N. J. A. Sloane, Feb 25 2017
EXTENSIONS
More terms from Alois P. Heinz, Jan 02 2018
STATUS
approved

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Last modified April 23 18:16 EDT 2024. Contains 371916 sequences. (Running on oeis4.)