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A059284
Right edge of triangle in A059283.
2
1, 1, 3, 11, 47, 219, 1081, 5557, 29439, 159611, 881405, 4940385, 28035205, 160751005, 929923395, 5420717819, 31809479855, 187757573787, 1114012352029, 6640357243537, 39746256802185, 238796968208537, 1439587364576015
OFFSET
0,3
LINKS
FORMULA
G.f.: -(-2+(-3*w^2-6*w+1)^(1/2))/(1+w)^2.
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 *)
CROSSREFS
Sequence in context: A308227 A247313 A262607 * A118927 A217216 A301409
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jan 24 2001
STATUS
approved