OFFSET
1,6
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, 0, -1, -2, -3, -4, -5, ...
2, 3, 6, 11, 18, 27, 38, ...
2, 0, -8, -28, -66, -128, -220, ...
3, 3, 17, 81, 255, 623, 1293, ...
3, 2, -27, -234, -1009, -3102, -7743, ...
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
sign,tabl
AUTHOR
Seiichi Manyama, Jun 06 2021
STATUS
approved