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1, 2, 4, 2, 4, 4, 3, 6, 6, 9, 2, 4, 4, 6, 4, 4, 8, 8, 12, 8, 16, 2, 4, 4, 6, 4, 8, 4, 4, 8, 8, 12, 8, 16, 8, 16, 3, 6, 6, 9, 6, 12, 6, 12, 9, 4, 8, 8, 12, 8, 16, 8, 16, 12, 16, 2, 4, 4, 6, 4, 8, 4, 8, 6, 8, 4, 6, 12, 12, 18, 12, 24, 12, 24, 18, 24, 12, 36, 2, 4, 4, 6, 4, 8, 4, 8, 6, 8, 4, 12, 4
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OFFSET
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1,2
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COMMENTS
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Row sums = A143236: (1, 6, 10, 24, 20, 56, 32,...).
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LINKS
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Table of n, a(n) for n=1..91.
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FORMULA
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Triangle read by rows, A130209 * A000012 * A130209; 1<=k<=n. T(n,k) = d(n)*d(k), where d(n) & d(k) = A000005, the number of divisors of n or k.
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EXAMPLE
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First few rows of the triangle =
1;
2, 4;
2, 4, 4;
3, 6, 6, 9;
2, 4, 4, 6, 4;
4, 8, 8, 12, 8, 16;
2, 4, 4, 6, 4, 8, 4;
4, 8, 8, 12, 8, 16, 8, 16;
3, 6, 6, 9, 6, 12, 6, 12, 9;
...
T(9,6) = 12 = d(9)*d(6) = 3*4.
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CROSSREFS
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Cf. A000005, A143236.
Sequence in context: A074075 A184186 A004020 * A069465 A047947 A018838
Adjacent sequences: A143232 A143233 A143234 * A143236 A143237 A143238
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KEYWORD
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nonn,tabl
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AUTHOR
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Gary W. Adamson, Aug 01 2008
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STATUS
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approved
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