OFFSET
0,3
COMMENTS
Row sums are n+1 = Sum_{k=0..n} binomial(k,n-k)*2^(2k-n)*(-1)^(n-k). Diagonal sums are (-1)^n*A008346(n). The Riordan array (1,s+tx) defines T(n,k) = binomial(k,n-k)*s^k*(t/s)^(n-k). The row sums satisfy a(n) = s*a(n-1) + t*a(n-2) and the diagonal sums satisfy a(n) = s*a(n-2) + t*a(n-3).
Triangle T(n,k), 0 <= k <= n, read by rows given by [0, -1/2, 1/2, 0, 0, 0, 0, ...] DELTA [2, 0, 0, 0, 0, ...] where DELTA is the operator defined in A084938. - Philippe Deléham, Nov 10 2008
FORMULA
Number triangle T(n, k) = binomial(k, n-k)*2^k*(-1/2)^(n-k); columns have g.f. (2x-x^2)^k.
G.f. of column k of matrix power T^m = (1 - (1-x)^(2^m))^k for k >= 0, when including the leading zeros that appear above the diagonal. - Paul D. Hanna, Nov 15 2007
T(n,k) = 2*T(n-1,k-1) - T(n-2,k-1), with T(0,0)=1, T(n,k)=0 if k < 0 or if k > n. - Philippe Deléham, Nov 25 2013
G.f.: 1/(1-2*x*y+x^2*y). - R. J. Mathar, Aug 12 2015
EXAMPLE
Rows begin
1;
0, 2;
0, -1, 4;
0, 0, -4, 8;
0, 0, 1, -12, 16;
...
PROG
(PARI) /* Matrix power T^m formula: [T^m](n, k) = */ {T(n, k, m=1)=polcoeff((1 - (1-x +x*O(x^n))^(2^m) )^k, n)} \\ Paul D. Hanna, Nov 15 2007
CROSSREFS
KEYWORD
AUTHOR
Paul Barry, Sep 25 2004
STATUS
approved