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a(n) = least m such that if r and s in {1/2, 1/5, 1/8, ..., 1/(3n-1)} satisfy r < s, then r < k/m < (k+1)/m < s for some integer k.
4

%I #12 Jun 27 2022 18:53:16

%S 7,21,41,67,100,155,205,281,346,443,523,641,737,876,1027,1149,1321,

%T 1505,1651,1856,2073,2243,2481,2731,2993,3197,3480,3775,4082,4321,

%U 4649,4989,5341,5613,5986,6371,6768,7073,7491,7921,8363,8702,9165,9640,10127,10626,11009

%N a(n) = least m such that if r and s in {1/2, 1/5, 1/8, ..., 1/(3n-1)} satisfy r < s, then r < k/m < (k+1)/m < s for some integer k.

%C For a guide to related sequences, see A001000. - _Clark Kimberling_, Aug 12 2012

%H Clark Kimberling, <a href="/A024837/b024837.txt">Table of n, a(n) for n = 2..100</a>

%t leastSeparatorS[seq_, s_] := Module[{n = 1},

%t Table[While[Or @@ (Ceiling[n #1[[1]]] <

%t s + 1 + Floor[n #1[[2]]] &) /@ (Sort[#1, Greater] &) /@

%t Partition[Take[seq, k], 2, 1], n++]; n, {k, 2, Length[seq]}]];

%t t = Map[leastSeparatorS[1/(3*Range[50]-1), #] &, Range[5]];

%t t[[2]] (* A024837 *)

%t (* _Peter J. C. Moses_, Aug 06 2012 *)

%Y Cf. A001000, A024836, A024838.

%K nonn

%O 2,1

%A _Clark Kimberling_