OFFSET
1,2
LINKS
Alois P. Heinz, Antidiagonals n = 1..141, flattened
EXAMPLE
Square array A(n,k) begins:
: 1, 2, 6, 6, 30, 5, 35, 280, 2520, 252, ...
: 1, 1, 3, 12, 60, 10, 70, 140, 1260, 126, ...
: 2, 2, 1, 4, 20, 30, 210, 420, 420, 42, ...
: 6, 6, 3, 1, 5, 30, 210, 420, 420, 42, ...
: 6, 6, 12, 4, 1, 6, 42, 84, 84, 210, ...
: 30, 30, 60, 20, 5, 1, 7, 56, 504, 1260, ...
: 5, 5, 10, 30, 30, 6, 1, 8, 72, 180, ...
: 35, 35, 70, 210, 210, 42, 7, 1, 9, 90, ...
: 70, 70, 35, 105, 420, 84, 56, 8, 1, 10, ...
: 70, 70, 35, 105, 420, 84, 504, 72, 9, 1, ...
MAPLE
A:= proc(n, k) option remember; `if`(k=n, 1,
(r-> r*k/igcd(r, k)^2)(A(n, k+`if`(n>k, 1, -1))))
end:
seq(seq(A(n, 1+d-n), n=1..d), d=1..14);
MATHEMATICA
A[n_, k_] := A[n, k] = If[k == n, 1, Function[{r}, r*k/GCD[r, k]^2][A[n, k+If[n>k, 1, -1]]]]; Table[Table[A[n, 1+d-n], {n, 1, d}], {d, 1, 14}] // Flatten (* Jean-François Alcover, Dec 02 2014, translated from Maple *)
CROSSREFS
AUTHOR
Alois P. Heinz, Nov 06 2014
STATUS
approved