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A026752 a(n) = T(2n-1,n-2), T given by A026747.

%I A026752 #9 Oct 29 2019 21:10:16
%S A026752 1,7,39,201,1000,4885,23621,113543,543895,2600204,12417829,59278440,
%T A026752 282969385,1351124510,6454283276,30849969965,147555219782,
%U A026752 706274470775,3383203356648,16219148141581,77817618006364,373661751926702
%N A026752 a(n) = T(2n-1,n-2), T given by A026747.
%H A026752 G. C. Greubel, <a href="/A026752/b026752.txt">Table of n, a(n) for n = 2..500</a>
%p A026752 A026747 := proc(n,k) option remember;
%p A026752    if k=0 or k = n then 1;
%p A026752    elif type(n,'even') and k <= n/2 then
%p A026752         procname(n-1,k-1)+procname(n-2,k-1)+procname(n-1,k) ;
%p A026752    else
%p A026752        procname(n-1,k-1)+procname(n-1,k) ;
%p A026752    end if ;
%p A026752 end proc:
%p A026752 seq(A026747(2*n-1,n-2), n=2..30); # _G. C. Greubel_, Oct 29 2019
%t A026752 T[n_, k_]:= T[n, k]= If[k==0 || k==n, 1, If[EvenQ[n] && k<=n/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[2n-1, n-2], {n,2,30}] (* _G. C. Greubel_, Oct 29 2019 *)
%o A026752 (Sage)
%o A026752 @CachedFunction
%o A026752 def T(n, k):
%o A026752     if (k==0 or k==n): return 1
%o A026752     elif (mod(n,2)==0 and k<=n/2): return T(n-1,k-1) + T(n-2,k-1) + T(n-1,k)
%o A026752     else: return T(n-1,k-1) + T(n-1,k)
%o A026752 [T(2*n-1, n-2) for n in (2..30)] # _G. C. Greubel_, Oct 29 2019
%Y A026752 Cf. A026747, A026748, A026749, A026750, A026751, A026753, A026754, A026755, A026756, A026757.
%K A026752 nonn
%O A026752 2,2
%A A026752 _Clark Kimberling_