k appears k times (k odd).

Terms

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