A082187 - OEIS

%I #21 Apr 07 2020 10:56:35

%S 1,2,7,6,23,10,21,20,33,28,51,44,87,56,117,80,153,100,201,110,243,140,

%T 291,164,327,188,387,218,405,248,483,284,555,322,633,340,711,392,783,

%U 430,861,460,951,520,1029,550,1137,616,1251,664,1335,718,1365,778,1551

%N First row of square array A082025.

%H Alois P. Heinz, <a href="/A082187/b082187.txt">Table of n, a(n) for n = 1..200</a>

%p 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

%t dmax = 55 (* number of antidiagonals *);

%t a[1, 1] = 1; used = {1}; a[_, _] = 1;

%t 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[]]];

%t Do[If[EvenQ[d], Do[loop, {j, d, 1, -1}], Do[loop, {j, 1, d}]], {d, 2, dmax}];

%t Table[a[1, k], {k, 1, dmax}] (* _Jean-François Alcover_, Apr 07 2020 *)

%Y Cf. A082025, A082188, A082189, A082190.

%K nonn

%O 1,2

%A _Amarnath Murthy_, Apr 07 2003

%E More terms from _R. J. Mathar_, May 06 2006

%E Edited with further terms by _Alois P. Heinz_, Oct 07 2009