a(n) = Sum_{k=0..n} (-1)^k*A020985(k).

Terms

a(0) =1a(1) =0a(2) =1a(3) =2a(4) =3a(5) =2a(6) =1a(7) =0a(8) =1a(9) =0a(10) =1a(11) =2a(12) =1a(13) =2a(14) =3a(15) =4a(16) =5a(17) =4a(18) =5a(19) =6a(20) =7a(21) =6a(22) =5a(23) =4a(24) =3a(25) =4a(26) =3a(27) =2a(28) =3a(29) =2