cp's OEIS Frontend

A375889 a(1) = 1, a(2) = 3; for n > 2, a(n) is the smallest unused positive number such that a(n) shares a factor with a(n-1) and (a(n) AND a(n-1)) = min(a(n), a(n-1)), where AND is the binary AND operation.

%I A375889 #11 Oct 21 2024 08:59:11
%S A375889 1,3,15,5,45,9,27,18,2,6,4,12,8,10,14,30,16,20,22,54,32,34,38,36,39,
%T A375889 33,51,17,85,65,75,66,64,68,70,78,72,74,90,24,26,58,40,42,46,44,60,28,
%U A375889 62,48,50,55,35,63,7,119,21,87,69,93,81,117,52,116,80,82,86,84,92,76,94,88,120,56,122,96
%N A375889 a(1) = 1, a(2) = 3; for n > 2, a(n) is the smallest unused positive number such that a(n) shares a factor with a(n-1) and (a(n) AND a(n-1)) = min(a(n), a(n-1)), where AND is the binary AND operation.
%C A375889 The fixed points begin 1, 12, 284, 50726, 50764, 50770, 50772, 50811, although there are likely more.
%C A375889 The sequence is conjectured to be a permutation of the positive integers.
%H A375889 Scott R. Shannon, <a href="/A375889/b375889.txt">Table of n, a(n) for n = 1..10000</a>
%e A375889 a(4) = 5 as 5 shares a factor with a(3) = 15 and min(15,5) = 5 and (5 AND 15) = 101_2 AND 1111_2 = 101_2 = 5.
%Y A375889 Cf. A375890, A303767, A169837, A027750.
%K A375889 nonn
%O A375889 1,2
%A A375889 _Scott R. Shannon_, Sep 01 2024