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 A178471 #2 Mar 30 2012 17:35:24 %S A178471 1,0,1,0,0,1,0,1,0,1,0,0,0,0,1,0,2,1,1,0,1,0,0,0,0,0,0,1,0,4,0,2,0,1, %T A178471 0,1,0,0,2,0,0,1,0,0,1,0,8,0,4,1,2,0,1,0,1,0,1,1,0,0,0,0,0,0,0,1,0,16, %U A178471 4,8,0,5,0,2,1,1,0,1,0,1,2,1,0,0,0,0,0,0,0,0,1,0,33,1,16,0,8,1,4,0,2,0,1,0 %N A178471 Triangle where T(n,k) is the number of compositions of n where no pair of consecutive part sizes is relative prime, starting with a part of size k. %e A178471 The array starts: %e A178471 1 %e A178471 0 1 %e A178471 0 0 1 %e A178471 0 1 0 1 %e A178471 0 0 0 0 1 %e A178471 0 2 1 1 0 1 %o A178471 (PARI) am(n)=local(r);r=matrix(n,n,i,j,i==j);for(i=2,n,for(j=1,i-1,for(k=1,j,if(gcd(i-j,k)>1,r[i,i-j]+=r[j,k]))));r %Y A178471 Cf. A178470 (row sums). %K A178471 nonn,tabl %O A178471 1,17 %A A178471 _Franklin T. Adams-Watters_, May 28 2010