A355860 Triangle read by rows: T(n,k) = n*k/(n + k) if n+k divides n*k, otherwise T(n,k) = 0; n >= 1, k >= 1.

0, 0, 1, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 0, 4, 0, 0, 0, 0, 0, 6

Offset

1,10

Links

Table of n, a(n) for n=1..78.

Example

The triangle begins:
  0;
  0, 1;
  0, 0, 0;
  0, 0, 0, 2;
  0, 0, 0, 0, 0;
  0, 0, 2, 0, 0, 3;
and so on.

Mathematica

T[n_, k_] := If[Divisible[n*k, n + k], n*k/(n + k), 0]; Table[T[n, k], {n, 1, 12}, {k, 1, n}] // Flatten (* Amiram Eldar, Jul 20 2022 *)

Crossrefs

Sequence in context: A112314 A350872 A280799 * A104261 A028702 A083929

Adjacent sequences: A355857 A355858 A355859 * A355861 A355862 A355863

Keyword

nonn,tabl

Author

Ctibor O. Zizka, Jul 19 2022

Status

approved