%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