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A134866
Table read by antidiagonals: T(n,k) = sigma(gcd(n,k)).
4
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
OFFSET
1,5
COMMENTS
Previous name was: Triangle, antidiagonals of an array formed by A051731 * A127093 (transform).
Row sums give A094471.
LINKS
Michael De Vlieger, Table of n, a(n) for n = 1..11325 (rows n = 1..150, flattened)
FORMULA
T(n,k) = A000203(A050873(n,k)). - Michel Marcus, Dec 19 2022
EXAMPLE
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;
...
MATHEMATICA
Table[DivisorSigma[1, GCD[#, k]] &[n - k + 1], {n, 13}, {k, n}] // Flatten (* Michael De Vlieger, Dec 19 2022 *)
PROG
(PARI) T(n, k) = sigma(gcd(n, k)); \\ Michel Marcus, Dec 19 2022
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Gary W. Adamson, Nov 14 2007
EXTENSIONS
New name and data corrected by Michel Marcus, Dec 19 2022
STATUS
approved