A026682 a(n) = A026681(2n,n).

1, 3, 10, 44, 174, 822, 3414, 16604, 70600, 348828, 1503802, 7504156, 32645122, 164014374, 718098056, 3625748104, 15950473396, 80839381968, 356946436186, 1814421022372, 8035178656538, 40941855317034, 181746522965214, 927880523400340

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

Cf. A026681.

Sequence in context: A041737 A279105 A246956 * A335635 A096804 A113059

Adjacent sequences: A026679 A026680 A026681 * A026683 A026684 A026685

Keyword

nonn

Author

Clark Kimberling

Status

approved