OFFSET
1,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..200
MAPLE
b:= proc(t) option remember; false end: b(1):= true: ncpr:= proc() local i, m; m:= args[1]; for i from 2 to nargs do if igcd (m, args[i])<>1 then return true fi od; false end: T:= proc(n, k) option remember; local h, t, l; if n<1 or k<1 or n=1 and k=1 then t:=1 else h:= 1- 2* irem(n+k, 2); l:= T(n-1, k), T(n, k-1), T(n-1, k-1), T(n+h, k-h); for t while b(t) or ncpr(t, l) do od fi; b(t):= true; t end: seq(T(1, k), k=1..60); # Alois P. Heinz, Oct 07 2009
MATHEMATICA
dmax = 55 (* number of antidiagonals *);
a[1, 1] = 1; used = {1}; a[_, _] = 1;
loop := For[i = d - j + 1; k = 1, True, k++, If[FreeQ[used, k] && AllTrue[ {a[i - 1, j + 1], a[i - 1, j], a[i - 1, j - 1], a[i, j - 1], a[i + 1, j - 1]}, CoprimeQ[k, #]&], AppendTo[used, k]; a[i, j] = k; Break[]]];
Do[If[EvenQ[d], Do[loop, {j, d, 1, -1}], Do[loop, {j, 1, d}]], {d, 2, dmax}];
Table[a[1, k], {k, 1, dmax}] (* Jean-François Alcover, Apr 07 2020 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Amarnath Murthy, Apr 07 2003
EXTENSIONS
More terms from R. J. Mathar, May 06 2006
Edited with further terms by Alois P. Heinz, Oct 07 2009
STATUS
approved