Tersum n + n.

Terms

a(0) =0a(1) =2a(2) =1a(3) =6a(4) =8a(5) =7a(6) =3a(7) =5a(8) =4a(9) =18a(10) =20a(11) =19a(12) =24a(13) =26a(14) =25a(15) =21a(16) =23a(17) =22a(18) =9a(19) =11a(20) =10a(21) =15a(22) =17a(23) =16a(24) =12a(25) =14a(26) =13a(27) =54a(28) =56a(29) =55