a(n) = |s(n) - n|, where s = A026239.

Terms

a(0) =0a(1) =2a(2) =3a(3) =2a(4) =3a(5) =3a(6) =2a(7) =3a(8) =2a(9) =1a(10) =1a(11) =1a(12) =1a(13) =3a(14) =4a(15) =7a(16) =3a(17) =11a(18) =4a(19) =11a(20) =16a(21) =19a(22) =7a(23) =19a(24) =22a(25) =27a(26) =32a(27) =33a(28) =11a(29) =37