a(n) = Sum_{k=1..n} floor(n/k)^4.

Terms

a(0) =1a(1) =17a(2) =83a(3) =274a(4) =644a(5) =1396a(6) =2502a(7) =4388a(8) =6919a(9) =10743a(10) =15385a(11) =22407a(12) =30233a(13) =41209a(14) =53853a(15) =70650a(16) =88636a(17) =113308a(18) =138654a(19) =172332a(20) =207984a(21) =252416a(22) =298002a(23) =358654a(24) =417873a(25) =492065a(26) =569061a(27) =663427a(28) =756053a(29) =875541