cp's OEIS Frontend

A381405 a(0) = 0; for n > 0, a(n) is the smallest unused number such that a(n) AND a(n-1) = 0, where AND is the binary AND operation, while the binary weight of a(n) does not equal that of a(n-1).

%I A381405 #11 Feb 23 2025 09:31:51
%S A381405 0,1,6,8,3,4,9,2,5,16,7,24,32,10,21,34,13,18,37,64,11,20,35,12,19,36,
%T A381405 25,66,28,33,14,17,38,65,22,40,23,72,39,80,15,48,67,60,128,26,68,27,
%U A381405 96,29,98,129,30,97,130,41,86,136,49,78,144,42,85,138,53,74,132,43,84,139,52,75,148,99,140,51,76,147,44,83,160,31,192,45,82,141,50,77,146,101
%N A381405 a(0) = 0; for n > 0, a(n) is the smallest unused number such that a(n) AND a(n-1) = 0, where AND is the binary AND operation, while the binary weight of a(n) does not equal that of a(n-1).
%C A381405 In the first 100000 terms the fixed points are 0, 1, 28, 76, 543, 1580, although more likely exist.
%H A381405 Scott R. Shannon, <a href="/A381405/b381405.txt">Table of n, a(n) for n = 0..10000</a>
%e A381405 a(3) = 8 = 1000_2 as 8 is unused and a(2) = 6 = 110_2, and 1000_2 AND 110_2 = 0 while the binary weights of 8 and 6 are 1 and 2 respectively.
%Y A381405 Cf. A000120, A129760, A061712, A057168, A381406.
%K A381405 nonn,base
%O A381405 0,3
%A A381405 _Scott R. Shannon_, Feb 22 2025