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A026761 a(n) = T(2n, n-2), T given by A026758.

%I A026761 #10 Nov 01 2019 03:55:11
%S A026761 1,8,48,259,1328,6622,32483,157739,761128,3657815,17534231,83925062,
%T A026761 401363296,1918822635,9173429111,43866599736,209853869150,
%U A026761 1004463716937,4810867131369,23057388013314,110588897473219,530808778620583
%N A026761 a(n) = T(2n, n-2), T given by A026758.
%H A026761 G. C. Greubel, <a href="/A026761/b026761.txt">Table of n, a(n) for n = 2..500</a>
%p A026761 T:= proc(n,k) option remember;
%p A026761    if n<0 then 0;
%p A026761    elif k=0 or k = n then 1;
%p A026761    elif type(n,'odd') and k <= (n-1)/2 then
%p A026761         procname(n-1,k-1)+procname(n-2,k-1)+procname(n-1,k) ;
%p A026761    else
%p A026761        procname(n-1,k-1)+procname(n-1,k) ;
%p A026761    end if ;
%p A026761 end proc;
%p A026761 seq(T(2*n,n-2), n=2..30); # _G. C. Greubel_, Oct 31 2019
%t A026761 T[n_, k_]:= T[n, k]= If[n<0, 0, If[k==0 || k==n, 1, If[OddQ[n] && k<=(n - 1)/2, T[n-1, k-1] + T[n-2, k-1] + T[n-1, k], T[n-1, k-1] + T[n-1, k] ]]]; Table[T[2 n, n-2], {n, 2, 30}] (* _G. C. Greubel_, Oct 31 2019 *)
%o A026761 (Sage)
%o A026761 @CachedFunction
%o A026761 def T(n, k):
%o A026761     if (n<0): return 0
%o A026761     elif (k==0 or k==n): return 1
%o A026761     elif (mod(n,2)==1 and k<=(n-1)/2): return T(n-1,k-1) + T(n-2,k-1) + T(n-1,k)
%o A026761     else: return T(n-1,k-1) + T(n-1,k)
%o A026761 [T(2*n, n-2) for n in (2..30)] # _G. C. Greubel_, Oct 31 2019
%Y A026761 Cf. A026758, A026759, A026760, A026762, A026763, A026764, A026765, A026766, A026767, A026768.
%K A026761 nonn
%O A026761 2,2
%A A026761 _Clark Kimberling_