A026964 a(n) = Sum_{k=0..n-3} T(n,k) * T(n,k+3), with T given by A026626.

1, 12, 77, 434, 1978, 8830, 37409, 156474, 644305, 2632506, 10684360, 43166246, 173768764, 697596990, 2794438513, 11174809302, 44626341136, 178018744896, 709505830530, 2825762505810, 11247704919634, 44749537493028, 177970696795672, 707580176408854, 2812524327414647

Offset: 3

Author

Clark Kimberling

Keywords

• nonn

Links

• G. C. Greubel, Table of n, a(n) for n = 3..1000

Crossrefs

Cf. A026626, A026627, A026628, A026629, A026630, A026631, A026632.

Cf. A026633, A026634, A026635, A026636, A026961, A026962, A026963.

Cf. A026965.

Programs

Mathematica

T[n_, k_]:= T[n, k]= If[k==0 || k==n, 1, If[k==1 || k==n-1, Floor[3*n/2], T[n-1,k-1] +T[n-1,k]]]; (* T = A026626 *)
A262964[n_]:= Sum[T[n,k]*T[n,k+3], {k,0,n-3}];
Table[A262964[n], {n,3,40}] (* G. C. Greubel, Jun 23 2024 *)

SageMath

@CachedFunction
def T(n, k): # T = A026626
    if (k==0 or k==n): return 1
    elif (k==1 or k==n-1): return int(3*n//2)
    else: return T(n-1, k-1) + T(n-1, k)
def A262964(n): return sum( T(n,k)*T(n,k+3) for k in range(n-2))
[A262964(n) for n in range(3,41)] # G. C. Greubel, Jun 23 2024

Extensions

More terms from Sean A. Irvine, Oct 20 2019