A266093 Number of B-diagrams G such that the number of vertices of G is |G|=n.

1, 4, 36, 372, 4372, 57396, 828020, 12962164, 218098356, 3915198836, 74543140404, 1497946963316, 31640513815604, 700059941981812, 16175777760450868, 389308305885650804, 9736819496150623284, 252548355023773152372

Offset

0,2

Comments

For a precise definition see the Bousbaa et al. link.

Links

Table of n, a(n) for n=0..17.

Imad Eddine Bousbaa, Ali Chouria, Jean-Gabriel Luque, A combinatorial Hopf algebra for the boson normal ordering problem, arXiv:1512.05937 [math.CO], 2015.

Mathematica

T[0, 0] = 1; T[p_, q_] := T[p, q] = Sum[l! Binomial[j, l] Binomial[q - k + l, l] Binomial[i, j] Binomial[i, k] T[p - i, q - k + l], {i, 1, p}, {j, 0, i}, {k, 0, i}, {l, 0, j}]; a[n_] := Sum[T[n, q], {q, 0, n}]; Table[ a[n], {n, 0, 20}] (* Jean-François Alcover, Dec 21 2015 *)

Crossrefs

Cf. A265199.

Sequence in context: A163455 A371772 A138736 * A198638 A358954 A019999

Adjacent sequences: A266090 A266091 A266092 * A266094 A266095 A266096

Keyword

nonn

Author

Michel Marcus, Dec 21 2015

Status

approved