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A127571
Triangle T(n,k) = phi(n/k)*sigma(k) if k divides n, else 0.
0
1, 1, 3, 2, 0, 4, 2, 3, 0, 7, 4, 0, 0, 0, 6, 2, 6, 4, 0, 0, 12, 6, 0, 0, 0, 0, 0, 8, 4, 6, 0, 7, 0, 0, 0, 15, 6, 0, 8, 0, 0, 0, 0, 0, 13, 4, 12, 0, 0, 6, 0, 0, 0, 0, 18
OFFSET
1,3
FORMULA
T(n,k) = sum_{j=k..n} A054523(n,j)* A130208(j,k), product of the two infinite lower triangular matrices.
T(n,1) = A000010(n).
T(n,n) = A000203(n).
EXAMPLE
First few rows of the triangle are:
1;
1, 3;
2, 0, 4;
2, 3, 0, 7;
4, 0, 0, 0, 6;
2, 6, 4, 0, 0, 12;
...
CROSSREFS
Cf. A000203, A000010, A038040 (row sums), A054523.
Sequence in context: A341413 A290794 A328178 * A194662 A143612 A353160
KEYWORD
nonn,tabl
AUTHOR
Gary W. Adamson, Jan 19 2007
STATUS
approved