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A127571
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Triangle T(n,k) = phi(n/k)*sigma(k) if k divides n, else 0.
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0
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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
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OFFSET
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1,3
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LINKS
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FORMULA
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T(n,k) = sum_{j=k..n} A054523(n,j)* A130208(j,k), product of the two infinite lower triangular matrices.
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EXAMPLE
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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;
...
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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