OFFSET
0,8
COMMENTS
Riordan array (1, x*(1-x)^2/(1-3*x+x^2)).
Antidiagonal sums: see A052946.
LINKS
Michael De Vlieger, Table of n, a(n) for n = 0..11475 (rows 0 <= n <= 150).
FORMULA
Sum_{k=0..n} T(n,k) = A204200(n+1).
T(n,k) = 3*T(n-1,k) + T(n-1,k-1) + T(n-3,k-1) - T(n-2,k) - 2*T(n-2,k-1).
G.f.: (-1 + 3*x - x^2)/(-1 + 3*x - x^2 + x*y - 2*x^2*y + x^3*y). - R. J. Mathar, Aug 11 2015
T(n,m) = Sum_{k=0..n-1} C(k,m-1)*C(n-2*m+k,n-k-1), T(0,0)=1. - Vladimir Kruchinin, Sep 27 2018
EXAMPLE
Triangle begins:
1;
0, 1;
0, 1, 1;
0, 3, 2, 1;
0, 8, 7, 3, 1;
0, 21, 22, 12, 4, 1;
0, 55, 67, 43, 18, 5, 1;
0, 144, 200, 147, 72, 25, 6, 1;
MATHEMATICA
Table[Sum[Binomial[k, m - 1] Binomial[n - 2 m + k, n - k - 1], {k, 0, n - 1}] + Boole[n == m == 0], {n, 0, 9}, {m, 0, n}] // Flatten (* Michael De Vlieger, Sep 26 2018 *)
PROG
(Maxima)
T(n, m):= if n=0 and m=0 then 1 else sum(binomial(k, m-1)*binomial(n-2*m+k, n-k-1), k, 0, n-1); /* Vladimir Kruchinin, Sep 27 2018 */
(PARI) T(n, k) = if ((n==0) && (k==0), 1, sum(i=0, n-1, binomial(i, k-1)*binomial(n-2*k+i, n-i-1))); \\ Michel Marcus, Sep 27 2018
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Philippe Deléham, Jan 16 2012
STATUS
approved