A059284 Right edge of triangle in A059283.

1, 1, 3, 11, 47, 219, 1081, 5557, 29439, 159611, 881405, 4940385, 28035205, 160751005, 929923395, 5420717819, 31809479855, 187757573787, 1114012352029, 6640357243537, 39746256802185, 238796968208537, 1439587364576015

Offset: 0

Author

N. J. A. Sloane, Jan 24 2001

Keywords

• nonn

Links

• G. C. Greubel, Table of n, a(n) for n = 0..1000

Crossrefs

Cf. A059283, A059226.

Programs

Mathematica

T[0,0] = 1; T[n_,0] = 0; T[n_, k_] /; 0 <= k <= n := T[n, k] = T[n, k - 1] + T[n - 1, k - 1] + T[n - 1, k] + T[n - 2, k - 1]; T[, ] = 0; Table[T[n,n], {n,0,25}] (* G. C. Greubel, Jan 04 2016 *)

Formula

G.f.: -(-2+(-3*w^2-6*w+1)^(1/2))/(1+w)^2.