a(n) = Sum_{d|n, n/d==1 mod 4} d^6 - Sum_{d|n, n/d==3 mod 4} d^6.

Terms

a(0) =1a(1) =64a(2) =728a(3) =4096a(4) =15626a(5) =46592a(6) =117648a(7) =262144a(8) =530713a(9) =1000064a(10) =1771560a(11) =2981888a(12) =4826810a(13) =7529472a(14) =11375728a(15) =16777216a(16) =24137570a(17) =33965632a(18) =47045880a(19) =64004096a(20) =85647744a(21) =113379840a(22) =148035888a(23) =190840832a(24) =244156251a(25) =308915840a(26) =386889776