Search: id:A131377 Results 1-1 of 1 results found. %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 Search completed in 0.001 seconds