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A127375
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Triangle, row sums = sum of gcd(k,n) for 1<=k<=n; left column = sigma(n).
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1
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1, 3, 0, 4, 1, 0, 7, 0, 1, 0, 6, 1, 1, 1, 0, 12, 0, 0, 1, 0, 8, 1, 1, 1, 1, 1, 0, 15, 0, 3, 0, 1, 0, 1, 0, 13, 4, 0, 1, 1, 0, 1, 1, 0, 18, 2, 3, 2, 0, 0, 1, 0, 1, 0
(list; table; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Left column = sigma(n), A000203: (1, 3, 4, 7, 6, 12...); row sums = A018804, sum of gcd(k,n) for 1<=k<=n: (1,3, 5, 8, 9, 15, 13,..)
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FORMULA
| A126988 * A054521, as infinite lower triangular matrices.
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EXAMPLE
| First few rows of the triangle are:
1;
3, 0;
4, 1, 0;
7, 0, 1, 0;
6, 1, 1, 1, 0;
12, 2, 0, 0, 1, 0;
8, 1, 1, 1, 1, 1, 0;
...
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CROSSREFS
| Cf. A126988, A054521, A018804, A000203.
Sequence in context: A060034 A035544 A129718 * A195084 A138376 A077140
Adjacent sequences: A127372 A127373 A127374 * A127376 A127377 A127378
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KEYWORD
| nonn,tabl
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AUTHOR
| Gary W. Adamson (qntmpkt(AT)yahoo.com), Jan 12 2007
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