A288140
Number of Dyck paths of semilength n such that the number of peaks is weakly decreasing from lower to higher levels.
Original entry on oeis.org
1, 1, 1, 3, 4, 12, 28, 63, 177, 455, 1233, 3383, 9359, 26809, 77078, 223201, 653982, 1934508, 5783712, 17431660, 52879184, 161386859, 495432345, 1530191918, 4754079840, 14849407892, 46604383972, 146897291083, 464892421363, 1477052536749, 4711124635655
Offset: 0
. a(5) = 12:
. /\ /\ /\
. /\/\/\/\/\ /\/\/\/ \ /\/\/ \/\ /\/ \/\/\
.
. /\ /\/\ /\/\ /\/\
. / \/\/\/\ /\/\/ \ /\/ \/\ / \/\/\
.
. /\ /\ /\ /\
. /\/ \ / \/\ /\/ \ / \/\
. /\/ \ /\/ \ / \/\ / \/\ .
-
b:= proc(n, k, j) option remember; `if`(n=j, 1, add(add(
b(n-j, t, i)*binomial(i, t)*binomial(j-1, i-1-t),
t=max(k, i-j)..min(n-j, i-1)), i=1..n-j))
end:
a:= n-> `if`(n=0, 1, add(b(n, k$2), k=1..n)):
seq(a(n), n=0..31);
-
b[n_, k_, j_] := b[n, k, j] = If[n == j, 1, Sum[Sum[b[n - j, t, i]* Binomial[i, t]*Binomial[j - 1, i - 1 - t], {t, Max[k, i - j], Min[n - j, i - 1]}], {i, 1, n - j}]];
a[n_] := If[n == 0, 1, Sum[b[n, k, k], {k, 1, n}]];
Table[a[n], {n, 0, 31}] (* Jean-François Alcover, May 29 2018, from Maple *)
A288141
Number of Dyck paths of semilength n such that the number of peaks is strongly decreasing from lower to higher levels.
Original entry on oeis.org
1, 1, 1, 1, 4, 5, 10, 22, 46, 148, 324, 722, 1843, 4634, 12537, 34248, 95711, 266761, 724689, 1983267, 5553902, 15900083, 46201546, 135511171, 400668869, 1189723253, 3535186203, 10516298421, 31405658622, 94378367065, 285623516777, 870481565252, 2671088133010
Offset: 0
a(5) = 5:
/\ /\ /\ /\
/\/\/\/\/\ /\/\/\/ \ /\/\/ \/\ /\/ \/\/\ / \/\/\/\
-
b:= proc(n, k, j) option remember; `if`(n=j, 1, add(add(
b(n-j, t, i)*binomial(i, t)*binomial(j-1, i-1-t),
t=max(k+1, i-j)..min(n-j, i-1)), i=1..n-j))
end:
a:= n-> `if`(n=0, 1, add(b(n, k$2), k=1..n)):
seq(a(n), n=0..34);
-
b[n_, k_, j_] := b[n, k, j] = If[n == j, 1, Sum[Sum[b[n - j, t, i]* Binomial[i, t]*Binomial[j - 1, i - 1 - t], {t, Max[k + 1, i - j], Min[n - j, i - 1]}], {i, 1, n - j}]];
a[n_] := If[n == 0, 1, Sum[b[n, k, k], {k, 1, n}]];
Table[a[n], {n, 0, 34}] (* Jean-François Alcover, May 29 2018, from Maple *)
A288146
Number of Dyck paths of semilength n such that the number of peaks is weakly increasing from lower to higher levels and no positive level is peakless.
Original entry on oeis.org
1, 1, 1, 3, 3, 13, 28, 65, 199, 540, 1468, 4188, 12328, 36870, 110181, 331226, 1012241, 3137822, 9796834, 30695164, 96658857, 306575170, 979485119, 3148413910, 10169223709, 32983822120, 107413795300, 351235602807, 1153308804255, 3802294411213, 12581993628872
Offset: 0
a(3) = 3:
/\ /\
/\/\/\ /\/ \ / \/\
a(4) = 3:
/\/\ /\/\
/\/\/\/\ /\/ \ / \/\
-
b:= proc(n, k, j) option remember; `if`(n=j, 1, add(add(
b(n-j, t, i)*binomial(i, t)*binomial(j-1, i-1-t),
t=max(1, i-j)..min(k, n-j, i-1)), i=1..n-j))
end:
a:= n-> `if`(n=0, 1, add(b(n, k$2), k=1..n)):
seq(a(n), n=0..34);
-
b[n_, k_, j_] := b[n, k, j] = If[n == j, 1, Sum[Sum[b[n - j, t, i]* Binomial[i, t]*Binomial[j - 1, i - 1 - t], {t, Max[1, i - j], Min[k, n - j, i - 1]}], {i, 1, n - j}]];
a[n_] := If[n == 0, 1, Sum[b[n, k, k], {k, 1, n}]];
Table[a[n], {n, 0, 34}] (* Jean-François Alcover, May 29 2018, from Maple *)
Showing 1-3 of 3 results.