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Characteristic function of numbers with alternating parities of their digits in decimal representation.
11

%I #4 Aug 31 2013 17:13:07

%S 1,1,1,1,1,1,1,1,1,1,1,0,1,0,1,0,1,0,1,0,0,1,0,1,0,1,0,1,0,1,1,0,1,0,

%T 1,0,1,0,1,0,0,1,0,1,0,1,0,1,0,1,1,0,1,0,1,0,1,0,1,0,0,1,0,1,0,1,0,1,

%U 0,1,1,0,1,0,1,0,1,0,1,0,0,1,0,1,0,1

%N Characteristic function of numbers with alternating parities of their digits in decimal representation.

%C a(A030141(n)) = 1; a(A228709(n)) = 0;

%H Reinhard Zumkeller, <a href="/A228710/b228710.txt">Table of n, a(n) for n = 0..10000</a>

%H <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>

%F For n > 9: a(n) * a(n+1) = 0 and 0 <= a(n) + a(n+1) <= 1.

%o (Haskell)

%o a228710 n = fromEnum $ f (n `div` 10) (n `mod` 2) where

%o f x p = x == 0 || (x `mod` 2) /= p && f (x `div` 10) (1 - p)

%K nonn,base

%O 0

%A _Reinhard Zumkeller_, Aug 31 2013