a(n) = ceiling(n^2/11).

Terms

a(0) =0a(1) =1a(2) =1a(3) =1a(4) =2a(5) =3a(6) =4a(7) =5a(8) =6a(9) =8a(10) =10a(11) =11a(12) =14a(13) =16a(14) =18a(15) =21a(16) =24a(17) =27a(18) =30a(19) =33a(20) =37a(21) =41a(22) =44a(23) =49a(24) =53a(25) =57a(26) =62a(27) =67a(28) =72a(29) =77