A026682 - OEIS

%I #11 Aug 21 2022 11:50:12

%S 1,3,10,44,174,822,3414,16604,70600,348828,1503802,7504156,32645122,

%T 164014374,718098056,3625748104,15950473396,80839381968,356946436186,

%U 1814421022372,8035178656538,40941855317034,181746522965214,927880523400340

%N a(n) = A026681(2n,n).

%H Robert Israel, <a href="/A026682/b026682.txt">Table of n, a(n) for n = 0..1456</a>

%p T:= proc(n,k) option remember;

%p if k=0 or k=n then return 1 fi;

%p if min(k,n-k)::even then procname(n-1,k-1)+procname(n-1,k)

%p else procname(n-1,k-1)+procname(n-2,k-1)+procname(n-1,k)

%p fi

%p end proc:

%p seq(T(2*n,n),n=0..40); # _Robert Israel_, Jul 16 2019

%t T[n_, k_] := T[n, k] = If[k == 0 || k == n, 1, If[EvenQ[Min[k, n-k]], T[n-1, k-1] + T[n-1, k], T[n-1, k-1] + T[n-2, k-1] + T[n-1, k]]];

%t Table[T[2n, n], {n, 0, 23}] (* _Jean-François Alcover_, Aug 21 2022, after Maple code *)

%Y Cf. A026681.

%K nonn

%O 0,2

%A _Clark Kimberling_