A257831 - OEIS

%I #11 Jun 06 2020 16:53:00

%S 0,1,10,11,100,101,110,111,1000,1001,10,11,110,111,1100,1101,1110,

%T 1111,11000,11001,100,101,1010,1011,10100,10101,10110,10111,101000,

%U 101001,110,111,1110,1111,11100,11101,11110,11111,111000,111001,1000,1001,10010,10011

%N In decimal representation of n: replace each digit with its binary representation.

%C a(n) = n iff (largest digit of n) = 1: a(A007088(n)) = A007088(n);

%C a(n) = A007088(A080719(n)).

%H Reinhard Zumkeller, <a href="/A257831/b257831.txt">Table of n, a(n) for n = 0..10000</a>

%e .    n |  dec    -->  bin         |     a(n) |  A080719(n)

%e . -----+--------------------------+----------+------------

%e .  100 |  [1,0,0]  |  [1,0,0]     |     100  |          4

%e .  101 |  [1,0,1]  |  [1,0,1]     |     101  |          5

%e .  102 |  [1,0,2]  |  [1,0,10]    |    1010  |         10

%e .  103 |  [1,0,3]  |  [1,0,11]    |    1011  |         11

%e .  104 |  [1,0,4]  |  [1,0,100]   |   10100  |         20

%e .  105 |  [1,0,5]  |  [1,0,101]   |   10101  |         21

%e .  106 |  [1,0,6]  |  [1,0,110]   |   10110  |         22

%e .  107 |  [1,0,7]  |  [1,0,111]   |   10111  |         23

%e .  108 |  [1,0,8]  |  [1,0,1000]  |  101000  |         40

%e .  109 |  [1,0,9]  |  [1,0,1001]  |  101001  |         41

%e .  110 |  [1,1,0]  |  [1,1,0]     |     110  |          6

%e .  111 |  [1,1,1]  |  [1,1,1]     |     111  |          7

%e .  112 |  [1,1,2]  |  [1,1,10]    |    1110  |         14

%e .  113 |  [1,1,3]  |  [1,1,11]    |    1111  |         15

%e .  114 |  [1,1,4]  |  [1,1,100]   |   11100  |         28

%e .  115 |  [1,1,5]  |  [1,1,101]   |   11101  |         29

%e .  116 |  [1,1,6]  |  [1,1,110]   |   11110  |         30

%e .  117 |  [1,1,7]  |  [1,1,111]   |   11111  |         31

%e .  118 |  [1,1,8]  |  [1,1,1000]  |  111000  |         56

%e .  119 |  [1,1,9]  |  [1,1,1001]  |  111001  |         57

%e .  120 |  [1,2,0]  |  [1,10,0]    |    1100  |         12

%e .  121 |  [1,2,1]  |  [1,10,1]    |    1101  |         13

%e .  122 |  [1,2,2]  |  [1,10,10]   |   11010  |         26

%e .  123 |  [1,2,3]  |  [1,10,11]   |   11011  |         27

%e .  124 |  [1,2,4]  |  [1,10,100]  |  110100  |         52

%e .  125 |  [1,2,5]  |  [1,10,101]  |  110101  |         53  .

%t Table[FromDigits[Flatten[IntegerDigits[#,2]&/@IntegerDigits[n]]],{n,0,50}] (* _Harvey P. Dale_, Jun 06 2020 *)

%o (Haskell)

%o import Data.Maybe (mapMaybe)

%o a257831 = foldr (\b v -> 10 * v + b) 0 .

%o            concat . mapMaybe (flip lookup bin) . a031298_row

%o             where bin = zip [0..9] a030308_tabf

%o (Python)

%o def A257831(n):

%o ....return int(''.join((format(int(d),'b') for d in str(n))))

%o # _Chai Wah Wu_, May 10 2015

%Y Cf. A007088, A030308, A031298, A080719.

%K nonn,base

%O 0,3

%A _Reinhard Zumkeller_, May 10 2015