A082187 First row of square array A082025.

1, 2, 7, 6, 23, 10, 21, 20, 33, 28, 51, 44, 87, 56, 117, 80, 153, 100, 201, 110, 243, 140, 291, 164, 327, 188, 387, 218, 405, 248, 483, 284, 555, 322, 633, 340, 711, 392, 783, 430, 861, 460, 951, 520, 1029, 550, 1137, 616, 1251, 664, 1335, 718, 1365, 778, 1551

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

Cf. A082025, A082188, A082189, A082190.

Sequence in context: A365007 A082017 A072985 * A211368 A225101 A351823

Adjacent sequences: A082184 A082185 A082186 * A082188 A082189 A082190

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