OFFSET
0,2
LINKS
Robert Israel, Table of n, a(n) for n = 0..1456
MAPLE
T:= proc(n, k) option remember;
if k=0 or k=n then return 1 fi;
if min(k, n-k)::even then procname(n-1, k-1)+procname(n-1, k)
else procname(n-1, k-1)+procname(n-2, k-1)+procname(n-1, k)
fi
end proc:
seq(T(2*n, n), n=0..40); # Robert Israel, Jul 16 2019
MATHEMATICA
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]]];
Table[T[2n, n], {n, 0, 23}] (* Jean-François Alcover, Aug 21 2022, after Maple code *)
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved