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Riordan array ((1+x)^3,x).
1

%I #2 Mar 30 2012 18:59:15

%S 1,3,1,3,3,1,1,3,3,1,0,1,3,3,1,0,0,1,3,3,1,0,0,0,1,3,3,1,0,0,0,0,1,3,

%T 3,1,0,0,0,0,0,1,3,3,1,0,0,0,0,0,0,1,3,3,1,0,0,0,0,0,0,0,1

%N Riordan array ((1+x)^3,x).

%C Row sums are A115291. Diagonal sums are A113311. Inverse is A122432. Sequence array for C(3,n).

%F Number triangle T(n,k)=C(3,n-k)

%e Triangle begins

%e 1,

%e 3,1,

%e 3,3,1,

%e 1,3,3,1,

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

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

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

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

%K easy,nonn,tabl

%O 0,2

%A _Paul Barry_, Sep 04 2006