a(n) = Sum_{k=0..n} floor(sqrt(k)).

Terms

a(0) =0a(1) =1a(2) =2a(3) =3a(4) =5a(5) =7a(6) =9a(7) =11a(8) =13a(9) =16a(10) =19a(11) =22a(12) =25a(13) =28a(14) =31a(15) =34a(16) =38a(17) =42a(18) =46a(19) =50a(20) =54a(21) =58a(22) =62a(23) =66a(24) =70a(25) =75a(26) =80a(27) =85a(28) =90a(29) =95