a(n) = Sum_{k=1..n} floor(n/k)^k.

Terms

a(0) =1a(1) =3a(2) =5a(3) =10a(4) =12a(5) =26a(6) =28a(7) =52a(8) =73a(9) =115a(10) =117a(11) =295a(12) =297a(13) =439a(14) =713a(15) =1160a(16) =1162a(17) =2448a(18) =2450a(19) =4644a(20) =6832a(21) =8902a(22) =8904a(23) =23536a(24) =25639a(25) =33857a(26) =53247a(27) =84961a(28) =84963a(29) =192237