A055827 a(n) = T(2n+3,n), array T as in A055818.

1, 23, 144, 848, 4880, 27816, 157920, 895264, 5074272, 28772280, 163262704, 927203184, 5270629104, 29988361032, 170780080320, 973422085184, 5552990609344, 31702646247768, 181128948471888, 1035584204252560

Offset: 0

Author

Clark Kimberling, May 28 2000

Keywords

• nonn

Links

• G. C. Greubel, Table of n, a(n) for n = 0..250

Crossrefs

Cf. A055818, A055819, A055820, A055821, A055822, A055823, A055824, A055825, A055826, A055828, A055829.

Programs

Maple

T:= proc(i, j) option remember;
      if i=0 or j=0 then 1
    else add(add(T(h,m), m=0..j), h=0..i-1)
  fi; end:
seq(T(n+3, n), n=0..30); # G. C. Greubel, Jan 22 2020

Mathematica

T[i_, j_]:= T[i, j]= If[i==0 || j==0, 1, Sum[T[h, m], {h,0,i-1}, {m,0,j}]]; Table[T[n+3, n], {n,0,25}] (* G. C. Greubel, Jan 22 2020 *)

Sage

@CachedFunction
def T(i, j):
    if (i==0 or j==0): return 1
    else: return sum(sum(T(h,m) for m in (0..j)) for h in (0..i-1))
[T(n+3, n) for n in (0..30)] # G. C. Greubel, Jan 22 2020