cp's OEIS Frontend

A027064 a(n) = A027052(n, 2n-8).

%I A027064 #11 Nov 07 2019 08:28:23
%S A027064 1,1,3,11,37,125,421,1405,4637,15125,48777,155665,492157,1543269,
%T A027064 4804663,14865495,45745953,140118817,427445507,1299383403,3937901525,
%U A027064 11902380845,35891429675,108009437323,324455779889,973119941425
%N A027064 a(n) = A027052(n, 2n-8).
%H A027064 G. C. Greubel, <a href="/A027064/b027064.txt">Table of n, a(n) for n = 4..750</a>
%p A027064 T:= proc(n, k) option remember;
%p A027064       if k<0 or k>2*n then 0
%p A027064     elif k=0 or k=2 or k=2*n then 1
%p A027064     elif k=1 then 0
%p A027064     else add(T(n-1, k-j), j=1..3)
%p A027064       fi
%p A027064     end:
%p A027064 seq( T(n,2*n-8), n=4..30); # _G. C. Greubel_, Nov 06 2019
%t A027064 T[n_, k_]:= T[n, k]= If[k<0 || k>2*n, 0, If[k==0 || k==2 || k==2*n, 1, If[k==1, 0, Sum[T[n-1, k-j], {j, 3}]]]]; Table[T[n,2*n-8], {n,4,30}] (* _G. C. Greubel_, Nov 06 2019 *)
%o A027064 (Sage)
%o A027064 @CachedFunction
%o A027064 def T(n, k):
%o A027064     if (k<0 or k>2*n): return 0
%o A027064     elif (k==0 or k==2 or k==2*n): return 1
%o A027064     elif (k==1): return 0
%o A027064     else: return sum(T(n-1, k-j) for j in (1..3))
%o A027064 [T(n,2*n-8) for n in (4..30)] # _G. C. Greubel_, Nov 06 2019
%K A027064 nonn
%O A027064 4,3
%A A027064 _Clark Kimberling_