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Write n in binary, exchange digits '0' <-> '1'.
10

%I #26 Sep 18 2024 08:43:18

%S 1,0,1,0,11,10,1,0,111,110,101,100,11,10,1,0,1111,1110,1101,1100,1011,

%T 1010,1001,1000,111,110,101,100,11,10,1,0,11111,11110,11101,11100,

%U 11011,11010,11001,11000,10111,10110,10101,10100,10011,10010,10001,10000

%N Write n in binary, exchange digits '0' <-> '1'.

%C Binary representation of A035327.

%C A base-2 analog of A048379.

%H Robert Israel, <a href="/A256078/b256078.txt">Table of n, a(n) for n = 0..10000</a>

%p f:= proc(n) local L,i;

%p L:= convert(n,base,2);

%p add((1-L[i])*10^(i-1),i=1..nops(L))

%p end proc:

%p map(f, [$0..100]); # _Robert Israel_, Sep 17 2024

%t Table[FromDigits[IntegerDigits[n, 2] /. {0 -> 1, 1 -> 0}], {n, 0, 47}] (* or *)

%t Table[FromDigits@ IntegerDigits[BitXor[n, 2^IntegerPart[Log[2, n] + 1] - 1], 2], {n, 0, 47}] (* _Michael De Vlieger_, Mar 22 2015, the latter based on _Alonso del Arte_ at A035327 *)

%o (PARI) A256078(n)=!n+eval(Strchr(apply(d->49-d,binary(n))))

%o (Python)

%o def a(n): return int(bin(1 if n==0 else n^((1 << n.bit_length())-1))[2:])

%o print([a(n) for n in range(48)]) # _Michael S. Branicky_, Dec 21 2022

%Y Cf. A035327, A048379.

%K nonn,base,easy

%O 0,5

%A _M. F. Hasler_, Mar 22 2015