A210976 Square array T(n,k), n>=1, k>=1, read by antidiagonals in which column k lists the positive integers whose number of divisors is not k.

2, 3, 1, 4, 4, 1, 5, 6, 2, 1, 6, 8, 3, 2, 1, 7, 9, 5, 3, 2, 1, 8, 10, 6, 4, 3, 2, 1, 9, 12, 7, 5, 4, 3, 2, 1, 10, 14, 8, 7, 5, 4, 3, 2, 1, 11, 15, 10, 9, 6, 5, 4, 3, 2, 1, 12, 16, 11, 11, 7, 6, 5, 4, 3, 2, 1, 13, 18, 12, 12, 8, 7, 6, 5, 4, 3, 2, 1, 14, 20

Offset: 1

Author

Omar E. Pol, Aug 11 2012

Keywords

• nonn
• tabl

Comments

Column k lists the numbers j such that A000005(j) <> k.

Examples

			Column 2 lists the nonprimes A018252 because they are the positive integers whose number of divisors is not 2.
Array begins:
2,   1,  1,  1,  1,  1,  1,  1,  1,  1,
3,   4,  2,  2,  2,  2,  2,  2,  2,
4,   6,  3,  3,  3,  3,  3,  3,
5,   8,  5,  4,  4,  4,  4,
6,   9,  6,  5,  5,  5,
7,  10,  7,  7,  6,
8,  12,  8,  9,
9,  14, 10,
10, 15,
11,
		

Crossrefs

Columns (1-4): A020725, A018252, A213367, A210994.