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A026447 a(n) = least positive integer > a(n-1) and not a(i)*a(j)+2 for 1<=i<j<=n. 2

%I

%S 3,4,5,6,7,8,9,10,11,12,13,15,16,18,19,21,24,25,27,28,31,33,36,39,40,

%T 43,45,48,49,51,53,55,60,61,63,64,69,70,71,73,75,76,81,84,85,87,88,89,

%U 91,94,96,99,100,103,104,105,108,109,111,113

%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="/A026447/b026447.txt">Table of n, a(n) for n = 1..1000</a>

%t a = {3, 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. A026443 and references therein.

%K nonn

%O 1,1

%A _Clark Kimberling_

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Last modified January 27 01:45 EST 2021. Contains 340443 sequences. (Running on oeis4.)