A356250 Square array T(n,k), n >= 1, k >= 0, read by antidiagonals downwards, where T(n,k) = Sum_{j=1..n} (j * floor(n/j))^k.
1, 1, 2, 1, 4, 3, 1, 8, 8, 4, 1, 16, 22, 15, 5, 1, 32, 62, 57, 21, 6, 1, 64, 178, 219, 91, 33, 7, 1, 128, 518, 849, 405, 185, 41, 8, 1, 256, 1522, 3315, 1843, 1053, 247, 56, 9, 1, 512, 4502, 13017, 8541, 6065, 1523, 402, 69, 10, 1, 1024, 13378, 51339, 40171, 35253, 9571, 2948, 545, 87, 11
Offset: 1
Examples
Square array begins: 1, 1, 1, 1, 1, 1, 1, ... 2, 4, 8, 16, 32, 64, 128, ... 3, 8, 22, 62, 178, 518, 1522, ... 4, 15, 57, 219, 849, 3315, 13017, ... 5, 21, 91, 405, 1843, 8541, 40171, ... 6, 33, 185, 1053, 6065, 35253, 206345, ... 7, 41, 247, 1523, 9571, 61091, 394987, ...
Crossrefs
Programs
-
Mathematica
T[n_, k_] := Sum[(j * Floor[n/j])^k, {j, 1, n}]; Table[T[k, n - k], {n, 1, 11}, {k, 1, n}] // Flatten (* Amiram Eldar, Jul 31 2022 *) -
PARI
T(n, k) = sum(j=1, n, (j*(n\j))^k);
-
PARI
T(n, k) = if(k==0, n, sum(j=1, n, j^k*sumdiv(j, d, 1-(1-1/d)^k)));
Formula
T(n,k) = Sum_{j=1..n} j^k * Sum_{d|j} (1 - (1 - 1/d)^k) for k > 0.