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((1,x)-(x,x^2))^(-2) (using Riordan array notation).
1

%I #2 Mar 30 2012 18:59:13

%S 1,2,1,0,0,1,3,2,0,1,0,0,0,0,1,0,0,2,0,0,1,0,0,0,0,0,0,1,4,3,0,2,0,0,

%T 0,1,0,0,0,0,0,0,0,0,1,0,0,0,0,2,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,1,0,0,

%U 3,0,0,2,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,2,0,0,0,0,0,0,1

%N ((1,x)-(x,x^2))^(-2) (using Riordan array notation).

%C Square of number triangle A115361. Row sums are A115364.

%e Triangle begins

%e 1,

%e 2, 1,

%e 0, 0, 1,

%e 3, 2, 0, 1,

%e 0, 0, 0, 0, 1,

%e 0, 0, 2, 0, 0, 1,

%e 0, 0, 0, 0, 0, 0, 1,

%e 4, 3, 0, 2, 0, 0, 0, 1,

%e 0, 0, 0, 0, 0, 0, 0, 0, 1,

%e 0, 0, 0, 0, 2, 0, 0, 0, 0, 1,

%e 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,

%e 0, 0, 3, 0, 0, 2, 0, 0, 0, 0, 0, 1,

%K nonn,tabl

%O 0,2

%A _Paul Barry_, Jan 21 2006