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 A026451 a(n) = least positive integer > a(n-1) and not a(i)*a(j)+2 for i<=1<=j<=n, n >= 2. 2

%I #8 Mar 06 2016 05:31:46

%S 2,4,5,7,8,9,11,13,14,15,17,19,21,23,25,26,29,31,33,35,39,41,43,45,49,

%T 50,53,55,56,59,61,63,69,71,73,75,76,81,82,85,89,91,95,96,98,99,103,

%U 104,105,109,110,111,113,115,116,125,129,130

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

%H Ivan Neretin, <a href="/A026451/b026451.txt">Table of n, a(n) for n = 1..1000</a>

%t a = {2, 4}; used = {a[[1]]^2 + 2, a[[1]]*a[[2]] + 2, a[[2]]^2 + 2}; Do[k = a[[-1]] + 1; While[MemberQ[used, k], k++]; AppendTo[a, k]; used = Union[used, k*a + 2], {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 June 15 03:12 EDT 2024. Contains 373402 sequences. (Running on oeis4.)