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

Terms

a(0) =1a(1) =63a(2) =730a(3) =4031a(4) =15626a(5) =45990a(6) =117650a(7) =257983a(8) =532171a(9) =984438a(10) =1771562a(11) =2942630a(12) =4826810a(13) =7411950a(14) =11406980a(15) =16510911a(16) =24137570a(17) =33526773a(18) =47045882a(19) =62988406a(20) =85884500a(21) =111608406a(22) =148035890a(23) =188327590a(24) =244156251a(25) =304089030a(26) =387952660a(27) =474247150a(28) =594823322