A245570 Rectangular array A read by (upward) antidiagonals: A(n,k) = n/gcd(n,10^k), n,k >= 1.

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

Author

L. Edson Jeffery, Jul 25 2014

Keywords

• nonn
• tabl

Comments

Columns of A converge to A132740.

Examples

			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, ...
  ...
		

Crossrefs

Cf. A132740.

Programs

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 *)