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 A181105 #4 Mar 31 2012 20:08:10 %S A181105 1,2,0,3,0,0,0,2,0,0,5,0,0,0,0,0,0,2,0,0,0,7,0,0,0,0,0,0,0,0,0,2,0,0, %T A181105 0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,2,0,0,0,0,0,11,0,0,0,0,0,0,0,0,0,0,0,0, %U A181105 0,0,0,2,0,0,0,0,0,0,13,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,0,0,0,0,0,0,0 %N A181105 Triangle T(n,k) read by rows. T(n,k)=abs(A181101)*n/k. %C A181105 Let A=T(n,k)*T(n,k), B=A*A, C=B*B, D=C*C, and so on. Then the first column in the last matrix (D) converges to the natural numbers. Rows sums are (unsurprisingly) A020639. Except for the first column, the largest and last element in the columns are also A020639. %e A181105 Triangle starts: %e A181105 1, %e A181105 2,0, %e A181105 3,0,0, %e A181105 0,2,0,0, %e A181105 5,0,0,0,0, %e A181105 0,0,2,0,0,0, %e A181105 7,0,0,0,0,0,0, %e A181105 0,0,0,2,0,0,0,0, %e A181105 0,0,3,0,0,0,0,0,0, %e A181105 0,0,0,0,2,0,0,0,0,0, %e A181105 11,0,0,0,0,0,0,0,0,0,0, %e A181105 0,0,0,0,0,2,0,0,0,0,0,0, %e A181105 13,0,0,0,0,0,0,0,0,0,0,0,0, %Y A181105 Cf. A181101, A020639. %K A181105 nonn,tabl %O A181105 1,2 %A A181105 Mats Granvik, _Gary W. Adamson_, Oct 03 2010