cp's OEIS Frontend

A080719 Replace decimal digits with their binary values and convert back to decimal representation.

%I A080719 #21 May 22 2025 10:21:35
%S A080719 0,1,2,3,4,5,6,7,8,9,2,3,6,7,12,13,14,15,24,25,4,5,10,11,20,21,22,23,
%T A080719 40,41,6,7,14,15,28,29,30,31,56,57,8,9,18,19,36,37,38,39,72,73,10,11,
%U A080719 22,23,44,45,46,47,88,89,12,13,26,27,52,53,54,55,104,105,14,15,30,31,60,61,62
%N A080719 Replace decimal digits with their binary values and convert back to decimal representation.
%C A080719 m is a local maximum iff m == 9 modulo 10 (see A017377).
%C A080719 A257831 seen as binary numbers: A007088(a(n)) = A257831(n). - _Reinhard Zumkeller_, May 10 2015
%H A080719 Reinhard Zumkeller, <a href="/A080719/b080719.txt">Table of n, a(n) for n = 0..10000</a>
%e A080719 n=27 -> '2''7' -> '10''111' -> '10111' -> 23: a(27)=23.
%e A080719 See also A257831.
%t A080719 Table[FromDigits[Flatten[IntegerDigits[#,2]&/@IntegerDigits[n]],2],{n,80}] (* _Harvey P. Dale_, Aug 30 2014 *)
%o A080719 (Haskell)
%o A080719 import Data.Maybe (mapMaybe)
%o A080719 a080719 = foldr (\b v -> 2 * v + b) 0 .
%o A080719            concat . mapMaybe (flip lookup bin) . a031298_row
%o A080719             where bin = zip [0..9] a030308_tabf
%o A080719 -- _Reinhard Zumkeller_, May 10 2015
%o A080719 (Python)
%o A080719 def A080719(n):
%o A080719     return int(''.join((format(int(d),'b') for d in str(n))),2)
%o A080719 # _Chai Wah Wu_, May 10 2015
%Y A080719 Cf. A007088.
%Y A080719 Cf. A257831, A030308, A031298.
%K A080719 nonn,base
%O A080719 0,3
%A A080719 _Reinhard Zumkeller_, Mar 06 2003
%E A080719 a(0)=0 prepended and offset changed by _Reinhard Zumkeller_, May 10 2015