A082188 First column of square array A082025.

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

Links

Table of n, a(n) for n=1..55.

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

Cf. A082025, A082187, A082189, A082190.

Sequence in context: A305551 A306018 A076120 * A202499 A341319 A063780

Adjacent sequences: A082185 A082186 A082187 * A082189 A082190 A082191

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