OFFSET
0,12
COMMENTS
Riordan array (1/(1-x+x^2), x*(x-1)/(1-x+x^2)).
FORMULA
T(n,k) = T(n-1,k) + T(n-2,k-1) - T(n-1,k-1) - T(n-2,k).
G.f.: 1/(1+(y-1)*x+(1-y)*x^2).
EXAMPLE
Triangle begins :
1
1, -1
0, -1, 1
-1, 1, 1, -1
-1, 3, -2, -1, 1
0, 2, -5, 3, 1, -1
CROSSREFS
KEYWORD
sign,tabl
AUTHOR
Philippe Deléham, Dec 21 2011
STATUS
approved