Partial sums of round(n^2/5).

Terms

a(0) =0a(1) =0a(2) =1a(3) =3a(4) =6a(5) =11a(6) =18a(7) =28a(8) =41a(9) =57a(10) =77a(11) =101a(12) =130a(13) =164a(14) =203a(15) =248a(16) =299a(17) =357a(18) =422a(19) =494a(20) =574a(21) =662a(22) =759a(23) =865a(24) =980a(25) =1105a(26) =1240a(27) =1386a(28) =1543a(29) =1711