cp's OEIS Frontend

A375890 a(1) = 1; for n > 1, a(n) is the smallest unused positive number such that a(n) is coprime to a(n-1) and (a(n) AND a(n-1)) = min(a(n), a(n-1)), where AND is the binary AND operation.

%I A375890 #12 Oct 21 2024 08:58:53
%S A375890 1,3,2,7,4,5,13,8,9,11,10,27,16,17,19,18,23,6,31,12,29,20,21,53,32,33,
%T A375890 35,34,39,37,36,47,14,15,79,64,65,67,66,71,68,69,77,72,73,75,74,91,24,
%U A375890 25,57,40,41,43,42,59,26,63,22,87,70,103,38,55,48,49,51,50,119,52,61,28,93,76,109,44
%N A375890 a(1) = 1; for n > 1, a(n) is the smallest unused positive number such that a(n) is coprime to a(n-1) and (a(n) AND a(n-1)) = min(a(n), a(n-1)), where AND is the binary AND operation.
%C A375890 The fixed points begin 1, 8, 9, 7453, 9338, although there are likely more.
%C A375890 The sequence is conjectured to be a permutation of the positive integers.
%H A375890 Scott R. Shannon, <a href="/A375890/b375890.txt">Table of n, a(n) for n = 1..10000</a>
%H A375890 Scott R. Shannon, <a href="/A375890/a375890.png">Image of the first 100000 terms</a>. The green line is a(n) = n.
%e A375890 a(5) = 4 as 4 is coprime to a(4) = 7 and min(7,4) = 4 and (7 AND 4) = 111_2 AND 100_2 = 100_2 = 4.
%Y A375890 Cf. A375889, A303767, A169837, A027750.
%K A375890 nonn,look
%O A375890 1,2
%A A375890 _Scott R. Shannon_, Sep 01 2024