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A245570
Rectangular array A read by (upward) antidiagonals: A(n,k) = n/gcd(n,10^k), n,k >= 1.
0
1, 1, 1, 3, 1, 1, 2, 3, 1, 1, 1, 1, 3, 1, 1, 3, 1, 1, 3, 1, 1, 7, 3, 1, 1, 3, 1, 1, 4, 7, 3, 1, 1, 3, 1, 1, 9, 2, 7, 3, 1, 1, 3, 1, 1, 1, 9, 1, 7, 3, 1, 1, 3, 1, 1, 11, 1, 9, 1, 7, 3, 1, 1, 3, 1, 1, 6, 11, 1, 9, 1, 7, 3, 1, 1, 3, 1, 1, 13, 3, 11, 1, 9, 1, 7, 3, 1, 1, 3, 1, 1
OFFSET
1,4
COMMENTS
Columns of A converge to A132740.
EXAMPLE
Array A begins:
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, ...
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, ...
3, 3, 3, 3, 3, 3, 3, 3, 3, 3, ...
2, 1, 1, 1, 1, 1, 1, 1, 1, 1, ...
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, ...
3, 3, 3, 3, 3, 3, 3, 3, 3, 3, ...
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, ...
4, 2, 1, 1, 1, 1, 1, 1, 1, 1, ...
9, 9, 9, 9, 9, 9, 9, 9, 9, 9, ...
...
MATHEMATICA
Grid[Table[n/GCD[n, 10^k], {n, 12}, {k, 12}]] (* Array *)
Flatten[Table[(n - k + 1)/GCD[n - k + 1, 10^k], {n, 13}, {k, n}]] (* Array antidiagonals flattened *)
CROSSREFS
Cf. A132740.
Sequence in context: A064048 A336218 A016464 * A243925 A348282 A030727
KEYWORD
nonn,tabl
AUTHOR
L. Edson Jeffery, Jul 25 2014
STATUS
approved