%I #33 Jan 08 2019 08:39:00
%S 1,3,3,4,7,4,7,12,12,7,6,15,13,15,6,12,18,28,28,18,12,8,28,24,31,24,
%T 28,8,15,24,39,42,42,39,24,15,13,31,32,60,31,60,32,31,13,18,39,60,56,
%U 72,72,56,60,39,18,12,42,40,63,48,91,48,63,40,42,12,28,36,72,91,90,96,96,90,91,72,36,28
%N Square array read by antidiagonals upwards: T(n,k) = sigma(n*k), n >= 1, k >= 1.
%H <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>
%F T(n,k) = A000203(n*k).
%F T(n,k) = A000203(A003991(n,k)).
%e The corner of the square array begins:
%e A000203: 1, 3, 4, 7, 6, 12, 8, 15, 13, 18, 12, 28, ...
%e A062731: 3, 7, 12, 15, 18, 28, 24, 31, 39, 42, 36, 60, ...
%e A144613: 4, 12, 13, 28, 24, 39, 32, 60, 40, 72, 48, 91, ...
%e A193553: 7, 15, 28, 31, 42, 60, 56, 63, 91, 90, 84, 124, ...
%e A283118: 6, 18, 24, 42, 31, 72, 48, 90, 78, 93, 72, 168, ...
%e A224613: 12, 28, 39, 60, 72, 91, 96, 124, 120, 168, 144, 195, ...
%e A283078: 8, 24, 32, 56, 48, 96, 57, 120, 104, 144, 96, 224, ...
%e A283122: 15, 31, 60, 63, 90, 124, 120, 127, 195, 186, 180, 252, ...
%e A283123: 13, 39, 40, 91, 78, 120, 104, 195, 121, 234, 156, 280, ...
%e ...
%t Table[DivisorSigma[1, # k] &[m - k + 1], {m, 12}, {k, m}] // Flatten (* _Michael De Vlieger_, Dec 31 2018 *)
%Y First 9 rows (also first 9 columns) are A000203, A062731, A144613, A193553, A283118, A224613, A283078, A283122, A283123.
%Y Main diagonal gives A065764.
%Y Cf. A000203, A003991, A216626, A319073.
%K nonn,tabl
%O 1,2
%A _Omar E. Pol_, Sep 25 2018