OFFSET
1,5
FORMULA
G.f. of column k: (1/(1 - x)) * Sum_{j>=1} x^j * (1 - x^j)/(1 - k*x^j).
EXAMPLE
Square array begins:
1, 1, 1, 1, 1, 1, 1, ...
1, 2, 3, 4, 5, 6, 7, ...
2, 3, 6, 11, 18, 27, 38, ...
2, 4, 12, 32, 70, 132, 224, ...
3, 5, 21, 87, 263, 633, 1305, ...
3, 6, 41, 258, 1047, 3158, 7821, ...
MATHEMATICA
T[n_, 0] := Floor[(n + 1)/2]; T[n_, k_] := Sum[k^(Floor[n/j] - 1), {j, 1, n}]; Table[T[k, n - k], {n, 1, 12}, {k, 1, n}] // Flatten (* Amiram Eldar, Jun 06 2021 *)
PROG
(PARI) T(n, k) = sum(j=1, n, k^(n\j-1));
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Seiichi Manyama, Jun 06 2021
STATUS
approved