OFFSET
1,3
LINKS
Alois P. Heinz, Antidiagonals n = 1..20, flattened
EXAMPLE
Square array A(n,k) begins:
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, ...
2, 3, 2, 5, 2, 7, 2, 3, 2, 11, ...
0, 9, 10, 25, 3, 49, 10, 9, 5, 121, ...
0, 27, 50, 125, 9, 203, 50, 27, 25, 253, ...
0, 81, 250, 205, 21, 343, 250, 57, 82, 1331, ...
0, 171, 1250, 625, 26, 1379, 1250, 81, 125, 2783, ...
0, 243, 5050, 1025, 27, 1421, 2810, 171, 625, 5819, ...
0, 513, 6250, 2525, 63, 2401, 5050, 243, 2525, 11891, ...
0, 729, 11810, 3125, 81, 5887, 6250, 513, 3125, 14641, ...
0, 1539, 25250, 5125, 147, 9653, 14050, 729, 3362, 30613, ...
MAPLE
A:= proc() local h, p; p:= proc() [1] end;
proc(n, k) if k=1 then `if`(n<3, n, 0) else
while nops(p(k))<n do for h from 1+p(k)[-1]
while k&^h+1 mod h <> 0 do od;
p(k):= [p(k)[], h]
od; p(k)[n] fi
end
end():
seq(seq(A(n, 1+d-n), n=1..d), d=1..12);
MATHEMATICA
dmax = 12;
mmax = 2^(dmax+3);
col[k_] := col[k] = Select[Range[mmax], Divisible[k^#+1, #]&];
A[n_, k_] := If[n>2 && k==1, 0, col[k][[n]]];
Table[A[n, d-n+1], {d, 1, dmax}, {n, 1, d}] // Flatten (* Jean-François Alcover, Jan 05 2021 *)
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Alois P. Heinz, Mar 20 2020
STATUS
approved