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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
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
1,17
EXAMPLE
The array starts:
1
0 1
0 0 1
0 1 0 1
0 0 0 0 1
0 2 1 1 0 1
PROG
(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
CROSSREFS
Cf. A178470 (row sums).
Sequence in context: A293015 A293119 A293133 * A160381 A089311 A086784
KEYWORD
nonn,tabl
AUTHOR
STATUS
approved