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A134866
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Table read by antidiagonals: T(n,k) = sigma(gcd(n,k)).
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4
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1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 3, 4, 3, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 7, 1, 3, 1, 1, 1, 4, 1, 1, 4, 1, 1, 1, 3, 1, 3, 6, 3, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 4, 7, 1, 12, 1, 7, 4, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 3, 1, 3, 8, 3, 1, 3, 1, 3, 1
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OFFSET
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1,5
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COMMENTS
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Previous name was: Triangle, antidiagonals of an array formed by A051731 * A127093 (transform).
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LINKS
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FORMULA
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EXAMPLE
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First few rows of the array:
1, 1, 1, 1, 1, 1, 1, ...
1, 3, 1, 3, 1, 3, 1, ...
1, 1, 4, 1, 1, 4, 1, ...
1, 3, 1, 7, 1, 3, 1, ...
1, 1, 1, 1, 6, 1, 1, ...
...
First antidiagonals:
1;
1, 1;
1, 3, 1;
1, 1, 1, 1;
1, 3, 4, 3, 1;
1, 1, 1, 1, 1, 1;
1, 3, 1, 7, 1, 3, 1;
1, 1, 4, 1, 1, 4, 1, 1;
1, 3, 1, 3, 6, 3, 1, 3, 1;
...
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MATHEMATICA
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Table[DivisorSigma[1, GCD[#, k]] &[n - k + 1], {n, 13}, {k, n}] // Flatten (* Michael De Vlieger, Dec 19 2022 *)
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PROG
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CROSSREFS
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KEYWORD
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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