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 A128187 #6 Apr 16 2013 05:46:31 %S A128187 1,1,1,2,0,1,2,2,0,1,3,0,1,0,1,3,3,1,1,0,1,4,0,1,0,1,0,1,4,4,1,2,0,1, %T A128187 0,1,5,0,2,0,1,0,1,0,1,5,5,1,2,1,1,0,1,0,1,6,0,2,0,1,0,1,0,1,0,1,6,6, %U A128187 2,3,1,2,0,1,0,1,0,1,7,0,2,0,1,0,1,0,1,0,1,0,1,7,7,2,3,1,2,1,1 %N A128187 Matrix product A128174 * A051731 read by rows. %F A128187 A128174 * A051731 as infinite lower triangular matrices. %e A128187 First few rows of the triangle are: %e A128187 1; %e A128187 1, 1; %e A128187 2, 0, 1; %e A128187 2, 2, 0, 1; %e A128187 3, 0, 1, 0, 1; %e A128187 3, 3, 1, 1, 0, 1; %e A128187 4, 0, 1, 0, 1, 0, 1; %e A128187 4, 4, 1, 2, 0, 1, 0, 1; %e A128187 ... %p A128187 A128187 := proc(n,k) %p A128187 add( A128174(n,j)*A051731(j,k), j=k..n) ; %p A128187 end proc: # _R. J. Mathar_, Apr 16 2013 %Y A128187 Cf. A128188 (row sums), A128174, A051731. %K A128187 nonn,easy,tabl %O A128187 1,4 %A A128187 _Gary W. Adamson_, Mar 07 2007