a(n) = Sum_{ d >= 1, d divides n} (-1)^(n-d)*d^4.

Terms

a(0) =1a(1) =15a(2) =82a(3) =271a(4) =626a(5) =1230a(6) =2402a(7) =4367a(8) =6643a(9) =9390a(10) =14642a(11) =22222a(12) =28562a(13) =36030a(14) =51332a(15) =69903a(16) =83522a(17) =99645a(18) =130322a(19) =169646a(20) =196964a(21) =219630a(22) =279842a(23) =358094a(24) =391251a(25) =428430a(26) =538084a(27) =650942a(28) =707282a(29) =769980