a(n) = n - floor(sqrt(n)).

Terms

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