A288323 Number of Dyck paths of semilength n such that each positive level has exactly seven peaks.

1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 8, 216, 1800, 6600, 11880, 10296, 3432, 0, 64, 3744, 96768, 1454160, 14460480, 102586176, 544817856, 2237725512, 7268659712, 18954982080, 40057015680, 68941928016, 97350892224, 122456030112, 244967552640

Offset: 0

Author

Alois P. Heinz, Jun 07 2017

Keywords

• nonn

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..1000
• Wikipedia, Counting lattice paths

Crossrefs

Column k=7 of A288318.

Cf. A000108.

Programs

Maple

b:= proc(n, k, j) option remember;
     `if`(n=j, 1, add(b(n-j, k, i)*(binomial(i, k)
      *binomial(j-1, i-1-k)), i=1..min(j+k, n-j)))
    end:
a:= n-> `if`(n=0, 1, b(n, 7$2)):
seq(a(n), n=0..40);

Mathematica

b[n_, k_, j_] := b[n, k, j] = If[n == j, 1, Sum[b[n - j, k, i]*(Binomial[i, k]*Binomial[j - 1, i - 1 - k]), {i, 1, Min[j + k, n - j]}]];
a[n_] := If[n == 0, 1, b[n, 7, 7]];
Table[a[n], {n, 0, 40}] (* Jean-François Alcover, Jun 02 2018, from Maple *)