A383240 Rectangular array read by antidiagonals where row n contains the numbers of the form prime(n)*m^2, where prime(n) does not divide m.

2, 18, 3, 50, 12, 5, 98, 48, 20, 7, 162, 75, 45, 28, 11, 242, 147, 80, 63, 44, 13, 338, 192, 180, 112, 99, 52, 17, 450, 300, 245, 175, 176, 117, 68, 19, 578, 363, 320, 252, 275, 208, 153, 76, 23, 722, 507, 405, 448, 396, 325, 272, 171, 92, 29, 882, 588, 605

Offset

1,1

Links

Table of n, a(n) for n=1..58.

Example

Corner:
    2  18   50   98  162  242  338   450
    3  12   48   75  147  192  300   363
    5  20   45   80  180  245  320   405
    7  28   63  112  175  252  448   567
   11  44   99  176  275  396  539   704
   13  52  117  208  325  468  637   832
   17  68  153  272  425  612  833  1088
   19  76  171  304  475  684  931  1216

Mathematica

c[n_] := c[n] = Select[Range[100]^2, ! IntegerQ[#/Prime[n]] &]
r[n_] := Map[Times, Prime[n]*c[n]];
t = Table[r[n], {n, 1, 12}]; TableForm[t] (* A383240 array *)
w[n_, k_] := t[[n]][[k]];
Table[w[n - k + 1, k], {n, 12}, {k, n, 1, -1}] // Flatten (* A383240 sequence *)

Crossrefs

Cf. A000040, A000290, A336615.

Sequence in context: A077452 A353309 A113918 * A253603 A094048 A387642

Adjacent sequences: A383237 A383238 A383239 * A383241 A383242 A383243

Keyword

nonn,tabl

Author

Clark Kimberling, May 04 2025

Status

approved