a(n) = floor( Sum_{k=1..n} sqrt(k+1) ).

Terms

a(0) =1a(1) =3a(2) =5a(3) =7a(4) =9a(5) =12a(6) =15a(7) =18a(8) =21a(9) =24a(10) =28a(11) =31a(12) =35a(13) =39a(14) =43a(15) =47a(16) =51a(17) =56a(18) =60a(19) =65a(20) =69a(21) =74a(22) =79a(23) =84a(24) =89a(25) =94a(26) =100a(27) =105a(28) =111a(29) =116