%I #6 Mar 30 2012 18:50:54
%S 0,0,0,0,0,1,1,0,0,1,1,0,1,0,1,0,0,1,1,0,1,0,1,0,0,0,1,0,1,0,0,0,0,1,
%T 1,0,1,0,1,0,0,0,1,0,1,0,0,0,1,0,1,0,0,0,1,0,0,0,0,0,1,0,1,0,0,1,1,0,
%U 1,0,1,0,0,0,1,0,1,0,0,0,1,0,1,0,0,0,1,0,0,0,0,0,1,0,1,0,0,0,0,0,1,0,0,0,1
%N Characteristic function of numbers that can be written as p+2^k, where p is prime and p less than 2^k (A118957).
%C 0 <= a(n) <= 1, a(n) <= A109925(n);
%C a(A118956(n)) = 0, a(A118957(n)) = 1;
%C A118953(n) = a(A000040(n)).
%H <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>
%K nonn
%O 1,1
%A _Reinhard Zumkeller_, May 07 2006