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.
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, 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, 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
Offset: 1
Examples
The array starts: 1 0 1 0 0 1 0 1 0 1 0 0 0 0 1 0 2 1 1 0 1
Crossrefs
Cf. A178470 (row sums).
Programs
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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