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A082188
First column of square array A082025.
4
1, 3, 4, 9, 8, 27, 14, 39, 22, 57, 32, 81, 46, 105, 64, 147, 82, 189, 104, 225, 124, 273, 142, 315, 166, 345, 194, 375, 224, 465, 254, 525, 286, 615, 326, 705, 358, 777, 394, 855, 434, 939, 470, 1023, 524, 1113, 572, 1233, 620, 1329, 668, 1395, 722, 1545, 782
OFFSET
1,2
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(n, 1), n=1..60); # Alois P. Heinz, Oct 07 2009
MATHEMATICA
nmax = 55; a[1, 1] = 1; used = {1}; a[_, _] = 1;
loop := For[i = n-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[n], Do[loop, {j, n, 1, -1}], Do[loop, {j, 1, n}]], {n, 2, nmax}];
a[n_] := a[n, 1];
Array[a, nmax] (* Jean-François Alcover, Feb 19 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