%I A131377
%S A131377 1,1,0,1,1,0,0,1,1,1,1,0,0,1,1,1,1,0,0,1,1,1,1,0,0,0,0,0,0,1,1,0,0,0,0,
%T A131377 0,0,1,1,1,1,0,0,1,1,1,1,0,0,0,0,0,0,1,1,1,1,1,1,0,0,1,1,1,1,1,1,0,0,0,
%U A131377 0,1,1,0,0,0,0,0,0,1,1,1,1,0,0,0,0,0,0,1,1,1,1,1,1,1,1,0,0,0,0
%N A131377 Starting with 1, the sequence a(n) changes from 1 to 0 or back when the 
               next number n is a prime.
%e A131377 n = 0, 1, 2, 3, 4, 5, etc..
%e A131377 a(n)= 1, 1, 0, 1, 1, 0, etc.
%e A131377 Starting with 1 the sequence changes when we move from 1 to 2 because 
               2 is prime, again from 2 to 3 because also 3 is prime, then from 
               4 to 5 being 5 prime and so on.
%p A131377 P:=proc(n) local i,k; k:=1; for i from 0 by 1 to n do if isprime(i) then 
               if k=1 then k:=0; else k:=1; fi; fi; print(k); od; end: P(100);
%Y A131377 Cf. A131378.
%Y A131377 Sequence in context: A079559 A014577 A157926 this_sequence A077049 A124895 
               A089885
%Y A131377 Adjacent sequences: A131374 A131375 A131376 this_sequence A131378 A131379 
               A131380
%K A131377 easy,nonn
%O A131377 0,1
%A A131377 Paolo P. Lava & Giorgio Balzarotti (ppl(AT)spl.at), Jul 04 2007