A026595 a(n) = T(n, floor(n/2)), where T is given by A026584.

1, 1, 1, 1, 5, 8, 19, 22, 69, 121, 341, 406, 1203, 2155, 6336, 7624, 22593, 40717, 121483, 147001, 438533, 792351, 2381512, 2892044, 8677763, 15703156, 47419503, 57728737, 173984792, 315180458, 954961034, 1164727748, 3522101709

Offset

0,5

Links

G. C. Greubel, Table of n, a(n) for n = 0..1000

Formula

a(n) = A026584(n, floor(n/2))

Mathematica

T[n_, k_]:= T[n, k]= If[k==0 || k==2*n, 1, If[k==1 || k==2*n-1, Floor[n/2], If[EvenQ[n+k], T[n-1, k-2] + T[n-1, k], T[n-1, k-2] + T[n-1, k-1] + T[n-1, k] ]]]; (* T = A026584 *)
Table[T[n, Floor[n/2]], {n, 0, 40}] (* G. C. Greubel, Dec 13 2021 *)

Prog

(Sage)
@CachedFunction
def T(n, k):  # T = A026584
    if (k==0 or k==2*n): return 1
    elif (k==1 or k==2*n-1): return (n//2)
    else: return T(n-1, k-2) + T(n-1, k) if ((n+k)%2==0) else T(n-1, k-2) + T(n-1, k-1) + T(n-1, k)
[T(n, n//2) for n in (0..40)] # G. C. Greubel, Dec 13 2021

Crossrefs

Cf. A026584, A026585, A026587, A026589, A026590, A026591, A026592, A026593, A026594, A026596, A026597, A026598, A026599, A027282, A027283, A027284, A027285, A027286.

Sequence in context: A226902 A347136 A326826 * A037233 A197539 A034453

Adjacent sequences: A026592 A026593 A026594 * A026596 A026597 A026598

Keyword

nonn

Author

Clark Kimberling

Status

approved