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 A073152 #7 Mar 30 2012 18:36:32
%S A073152 1,1,2,3,4,7,9,12,15,24,31,40,49,58,89,113,144,171,198,229,342,431,
%T A073152 544,637,718,811,924,1355,1697,2128,2467,2746,3025,3364,3795,5492,
%U A073152 6847,8544,9837,10854,11815,12832,14125,15822,22669,28161
%N A073152 Triangle of numbers relating two simple context-free grammars (A052709 and A052705).
%C A073152 Sequence A052705 is the convolution of A052709.
%H A073152 D. Merlini, D. G. Rogers, R. Sprugnoli and M. C. Verri, <a href="http://dx.doi.org/10.4153/CJM-1997-015-x">On some alternative characterizations of Riordan arrays</a>, Canad. J. Math. 49 (1997) 301
%F A073152 Triangle {a(n, k), n >= 0, 0<=k<=n} defined by: a(0, 0)=1, a(n, 0)=A052709(n+1), a(n, n)=A052705(n+2), a(n, 0)=a(n-1, n-1) + a(n-2, n-2), a(n, k)=sum{j=0..k} A052709(j+1) * a(n-j, 0).
%e A073152 a(5,0)=a(3,3)+a(4,4)=24+89=113. a(5,3)=1*a(5,0)+1*a(4,0)+3*a(3,0)+9*a(2,0)=1*113+1*31+3*9+9*3=198. Rows: {1}; {1,2}; {3,4,7}; {9,12,15,24}; {31,40,49,58,89}; {113,144,171,198,229,342}; {431,544,637,718,811,924,1355}; {1697,2128,2467,2746,3025,3364,3795,5492}
%Y A073152 Cf. A052709, A052705.
%K A073152 easy,nonn,tabl
%O A073152 0,3
%A A073152 _Paul D. Hanna_, Jul 29 2002