a(n) = Sum_{d|n} (-1)^(n/d+1)*d^5.

Terms

a(0) =1a(1) =31a(2) =244a(3) =991a(4) =3126a(5) =7564a(6) =16808a(7) =31711a(8) =59293a(9) =96906a(10) =161052a(11) =241804a(12) =371294a(13) =521048a(14) =762744a(15) =1014751a(16) =1419858a(17) =1838083a(18) =2476100a(19) =3097866a(20) =4101152a(21) =4992612a(22) =6436344a(23) =7737484a(24) =9768751a(25) =11510114a(26) =14408200a(27) =16656728a(28) =20511150a(29) =23645064