A103181 In decimal representation of n: replace all even digits with 0 and all odd digits with 1.

0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 10, 11, 10, 11, 10, 11, 10, 11, 10, 11, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 10, 11, 10, 11, 10, 11, 10, 11, 10, 11, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 10, 11, 10, 11, 10, 11, 10, 11, 10, 11, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 10, 11, 10, 11, 10, 11, 10, 11, 10, 11, 0, 1, 0, 1, 0, 1

Offset: 0

Author

Reinhard Zumkeller, Mar 18 2005

Keywords

• nonn
• base
• easy

Examples

			199->'111': a(199)=111; 200->'000': a(200)=0;
299->'011': a(299)=11; 300->'100': a(300)=100.
		

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 0..9999

Crossrefs

Cf. A000035, A014263.

Programs

Haskell

import Data.List (unfoldr); import Data.Tuple (swap)
a103181_list = map a103181 [0..]
a103181 n = foldl f 0 $ reverse $ unfoldr g n where
   f v d = 10 * v + mod d 2
   g x = if x == 0 then Nothing else Just $ swap $ divMod x 10
-- Reinhard Zumkeller, Oct 04 2011

Mathematica

Table[FromDigits[If[EvenQ[#],0,1]&/@IntegerDigits[n]],{n,0,90}] (* Harvey P. Dale, Nov 08 2022 *)

PARI

a(n)=subst(Pol(apply(k->k%2, digits(n))),'x,10) \\ Charles R Greathouse IV, Jul 16 2013

Python

def A103181(n): return int(''.join(str(int(d) % 2) for d in str(n))) # Chai Wah Wu, Apr 09 2022

Formula

n = Sum(d(k)*10^k: 0<=d(k)<10) -> a(n) = Sum((d(k) mod 2)*10^k).

a(A014263(n)) = 0. - Reinhard Zumkeller, Oct 04 2011