A026423 - OEIS

%I #8 Mar 07 2016 08:32:03

%S 1,3,4,5,6,7,8,10,11,13,14,17,19,22,23,26,27,29,31,34,37,38,41,43,45,

%T 46,47,53,54,58,59,61,62,63,67,71,72,73,74,75,79,82,83,86,89,90,94,96,

%U 97,99,101,103,105,106,107,109,113,117,118,120

%N a(n) = least positive integer > a(n-1) and not a(i)*a(j) for 1<=i<=j<=n, n >= 2.

%H Ivan Neretin, <a href="/A026423/b026423.txt">Table of n, a(n) for n = 1..1000</a>

%t a = {1, 3}; used = {a[[1]]^2, a[[1]]*a[[2]], a[[2]]^2}; Do[k = a[[-1]] + 1; While[MemberQ[used, k], k++]; AppendTo[a, k]; used = Union[used, k*a], {n, 3, 60}]; a (* _Ivan Neretin_, Mar 07 2016 *)

%Y Cf. A026416 and references therein.

%K nonn

%O 1,2

%A _Clark Kimberling_