a(n) = Sum_{k=1..n} floor(n/k)^5.

Terms

a(0) =1a(1) =33a(2) =245a(3) =1058a(4) =3160a(5) =8054a(6) =17086a(7) =33860a(8) =60353a(9) =103437a(10) =164489a(11) =257945a(12) =380407a(13) =556001a(14) =779865a(15) =1085840a(16) =1457122a(17) =1958008a(18) =2544540a(19) =3312306a(20) =4205650a(21) =5336264a(22) =6618976a(23) =8254674a(24) =10059777a(25) =12298021a(26) =14792045a(27) =17829881a(28) =21130663a(29) =25189011