This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A112906 #3 Mar 30 2012 18:59:12
%S A112906 1,0,3,0,1,10,0,0,6,33,0,0,1,29,109,0,0,0,9,126,360,0,0,0,1,57,516,
%T A112906 1189,0,0,0,0,12,306,2034,3927,0,0,0,0,1,94,1491,7807,12970,0,0,0,0,0,
%U A112906 15,600,6813,29382,42837,0,0,0,0,0,1,140,3385,29737,108923,141481,0,0,0,0,0,0
%N A112906 A skew generalized Pascal triangle.
%C A112906 Main diagonal is A006190. Row sums are A007482. Column sums are A001076(n+1). Compare with [0,1/3,-1/3,0,0,..] DELTA [3,1/3,-1/3,0,0,...] where DELTA is the operator defined in A084938. A skewed version of the Riordan array (1/(1-3x-x^2),x/(1-3x-x^2)).
%F A112906 G.f.: 1/(1-3xy(1+x/3)-x^2*y^2); T(n, k)=sum{j=0..floor((2k-n)/2), C(k-j, n-k)C(2k-n, j)3^(2k-2j-n)}; T(n, k) = 3*T(n-1, k-1)+T(n-2, k-1)+T(n-2, k-2).
%e A112906 Triangle begins
%e A112906 1;
%e A112906 0, 3;
%e A112906 0, 1, 10;
%e A112906 0, 0, 6, 33;
%e A112906 0, 0, 1, 29, 109;
%e A112906 0, 0, 0, 9, 126, 360,
%e A112906 0, 0, 0, 1, 57, 516, 1189;
%e A112906 0, 0, 0, 0, 12, 306, 2034, 3927;
%e A112906 0, 0, 0, 0, 1, 94, 1491, 7809, 12970;
%Y A112906 Cf. A112899.
%K A112906 easy,nonn,tabl
%O A112906 0,3
%A A112906 _Paul Barry_, Oct 05 2005