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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
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 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,2

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

LINKS

Table of n, a(n) for n=1..35.

EXAMPLE

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

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 *)

CROSSREFS

Cf. A034444.

As an array, essentially the same as A125666.

Sequence in context: A277810 A180428 A130684 * A079178 A322365 A297553

Adjacent sequences: A295641 A295642 A295643 * A295645 A295646 A295647

KEYWORD

nonn,tabl,more

AUTHOR

Clark Kimberling, Jun 26 2018

STATUS

approved

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Last modified February 3 15:39 EST 2023. Contains 360035 sequences. (Running on oeis4.)