cp's OEIS Frontend

A337222 a(n) is the least number that can be obtained by replacing some square XX in the binary expansion of n by X.

%I A337222 #13 Aug 22 2020 18:50:50
%S A337222 0,1,2,1,2,5,2,3,4,5,2,5,4,5,6,3,4,9,10,9,4,5,10,11,8,9,6,11,12,13,6,
%T A337222 7,8,9,18,17,4,9,18,19,8,9,10,11,20,5,22,11,12,17,18,19,12,13,6,23,24,
%U A337222 25,14,27,12,13,14,7,8,17,18,19,34,17,34,35,8,9,18
%N A337222 a(n) is the least number that can be obtained by replacing some square XX in the binary expansion of n by X.
%C A337222 Leading zeros in binary expansions are ignored.
%C A337222 There are four fixed points: 0, 1, 2 and 5; their binary expansion is a squarefree string.
%H A337222 Rémy Sigrist, <a href="/A337222/b337222.txt">Table of n, a(n) for n = 0..8192</a>
%H A337222 Rémy Sigrist, <a href="/A337222/a337222.gp.txt">PARI program for A337222</a>
%H A337222 <a href="/index/Bi#binary">Index entries for sequences related to binary expansion of n</a>
%F A337222 a(A020330(n)) = n for any n > 0.
%e A337222 The first terms, in decimal and in binary, are:
%e A337222   n   a(n)  bin(n)  bin(a(n))
%e A337222   --  ----  ------  ---------
%e A337222    0     0       0          0
%e A337222    1     1       1          1
%e A337222    2     2      10         10
%e A337222    3     1      11          1
%e A337222    4     2     100         10
%e A337222    5     5     101        101
%e A337222    6     2     110         10
%e A337222    7     3     111         11
%e A337222    8     4    1000        100
%e A337222    9     5    1001        101
%e A337222   10     2    1010         10
%e A337222   11     5    1011        101
%e A337222   12     4    1100        100
%e A337222   13     5    1101        101
%e A337222   14     6    1110        110
%e A337222   15     3    1111         11
%e A337222   16     4   10000        100
%o A337222 (PARI) See Links section.
%Y A337222 Cf. A020330, A337223, A337224.
%K A337222 nonn,base
%O A337222 0,3
%A A337222 _Rémy Sigrist_, Aug 19 2020