cp's OEIS Frontend

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.

%I A383240 #11 May 09 2025 19:33:21
%S A383240 2,18,3,50,12,5,98,48,20,7,162,75,45,28,11,242,147,80,63,44,13,338,
%T A383240 192,180,112,99,52,17,450,300,245,175,176,117,68,19,578,363,320,252,
%U A383240 275,208,153,76,23,722,507,405,448,396,325,272,171,92,29,882,588,605
%N 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.
%e A383240 Corner:
%e A383240     2  18   50   98  162  242  338   450
%e A383240     3  12   48   75  147  192  300   363
%e A383240     5  20   45   80  180  245  320   405
%e A383240     7  28   63  112  175  252  448   567
%e A383240    11  44   99  176  275  396  539   704
%e A383240    13  52  117  208  325  468  637   832
%e A383240    17  68  153  272  425  612  833  1088
%e A383240    19  76  171  304  475  684  931  1216
%t A383240 c[n_] := c[n] = Select[Range[100]^2, ! IntegerQ[#/Prime[n]] &]
%t A383240 r[n_] := Map[Times, Prime[n]*c[n]];
%t A383240 t = Table[r[n], {n, 1, 12}]; TableForm[t] (* A383240 array *)
%t A383240 w[n_, k_] := t[[n]][[k]];
%t A383240 Table[w[n - k + 1, k], {n, 12}, {k, n, 1, -1}] // Flatten (* A383240 sequence *)
%Y A383240 Cf. A000040, A000290, A336615.
%K A383240 nonn,tabl
%O A383240 1,1
%A A383240 _Clark Kimberling_, May 04 2025