OFFSET
0,8
COMMENTS
LINKS
G. C. Greubel, Table of n, a(n) for the first 50 rows, flattened
FORMULA
Number triangle T(n, k) = Sum_{j=0..floor((n-k)/2)} C(n-k, j)*C(n-k-j, j)*k^j.
EXAMPLE
Rows begin
1;
1, 1;
1, 1, 1;
1, 3, 1, 1;
1, 7, 5, 1, 1;
1, 19, 13, 7, 1, 1;
MATHEMATICA
T[n_, 0] := 1; T[n_, k_] := Sum[Binomial[n - k, j]*Binomial[n - k - j, j]*k^j, {j, 0, Floor[(n - k)/2]}]; Table[T[n, k], {n, 0, 49}, {k, 0, n}] // Flatten (* G. C. Greubel, Mar 05 2017 *)
CROSSREFS
KEYWORD
AUTHOR
Paul Barry, Jul 14 2005
STATUS
approved