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
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
Programs
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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 *)
Comments