OFFSET
0,5
COMMENTS
A Galton triangle. Essentially the same as A187075.
FORMULA
T(n,k) = 2*k*T(n-1,k) + (2*k-1)*T(n-1,k-1), T(0,0) = 1, T(n,k) = 0 if k<0 or if k>n.
G.f.: F(x,t) = 1 + x*t + (2*x+3*x^2)*t^2/2! + (4*x+18*x^2+15*x^3)*t^3/3!+ ... = Sum_{n = 0..inf}R(n,x)*t^n/n!.
The row polynomials R(n,x) satisfy the recursion R(n+1,x) = 2*(x+x^2)*R'(n,x) + x*R(n,x) where ' indicates differentiation with respect to x.
EXAMPLE
Triangle begins :
1
0, 1
0, 2, 3
0, 4, 18, 15
0, 8, 84, 180, 105
0, 16, 360, 1500, 2100, 945
0, 32, 1488, 10800, 27300, 28350, 10395
CROSSREFS
KEYWORD
AUTHOR
Philippe Deléham, Feb 09 2013
STATUS
approved