A295644 Rectangular array, by antidiagonals; row 1 is the ordered list of all k having at most 2 unitary divisors; for n > 1, row n is the ordered list of all k having 2^n unitary divisors.

1, 2, 6, 3, 10, 30, 4, 12, 42, 210, 5, 14, 60, 330, 2310, 7, 15, 66, 390, 2730, 30030, 8, 18, 70, 420, 3570, 39270, 510510, 9, 20, 78, 462, 3990, 43890, 570570

Offset: 1

Author

Clark Kimberling, Jun 26 2018

Keywords

• nonn
• tabl
• more

Comments

Every positive integer occurs exactly once, so that as a sequence, this is a permutation of the positive integers.

row 1: A000961

row 2: A007774

row 3: A033992

row 4: A033993

col 1: A231209

Examples

			Northwest corner:
     1    2    3    4    5    7    8    9   11
     6   10   12   14   15   18   20   21   22
    30   42   60   66   70   78   84   90  102
   210  330  390  420  462  510  546  570  630
  2310 2730 3570 3990 4290 4620 4830 5460 5610
		

Crossrefs

Cf. A034444.

As an array, essentially the same as A125666.

Programs

Mathematica

z = 10000;
t = Table[2^PrimeNu[n], {n, 1, z}] ;(*  A035555 *)
r[n_] := Flatten[Position[t, 2^n]]; r[1] = Join[{1}, r[1]];
v[n_, k_] := r[n][[k]];
TableForm[Table[v[n, k], {n, 1, 5}, {k, 1, 15}]]  (* A295644 array *)
Table[v[n - k + 1, k], {n, 5}, {k, n, 1, -1}] // Flatten  (* A295644 sequence *)