a(n) = Sum_{d|n} (-1)^(d-1)*d^6.

Terms

a(0) =1a(1) =-63a(2) =730a(3) =-4159a(4) =15626a(5) =-45990a(6) =117650a(7) =-266303a(8) =532171a(9) =-984438a(10) =1771562a(11) =-3036070a(12) =4826810a(13) =-7411950a(14) =11406980a(15) =-17043519a(16) =24137570a(17) =-33526773a(18) =47045882a(19) =-64988534a(20) =85884500a(21) =-111608406a(22) =148035890a(23) =-194401190a(24) =244156251a(25) =-304089030a(26) =387952660a(27) =-489306350a(28) =594823322a(29) =-718639740