A026457 - OEIS

%I #8 Mar 06 2016 10:22:20

%S 2,4,5,7,9,10,11,13,14,15,17,19,21,22,23,25,27,29,30,31,35,37,39,41,

%T 45,46,47,49,51,55,57,59,62,64,65,67,69,70,71,77,78,79,81,84,85,87,91,

%U 94,95,99,101,102,104,105,107,109,110,111,119

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

%H Ivan Neretin, <a href="/A026457/b026457.txt">Table of n, a(n) for n = 1..1000</a>

%t a = {2, 4}; used = {a[[1]]*a[[2]] - 2}; Do[k = a[[-1]] + 1; While[MemberQ[used, k], k++]; used = Union[used, k*a - 2]; AppendTo[a, k], {n, 3, 60}]; a (* _Ivan Neretin_, Mar 06 2016 *)

%Y Cf. A026453 and references therein.

%K nonn

%O 1,1

%A _Clark Kimberling_