a(n) = Sum_{d|n} (-1)^(n/d+1)*d^11.

Terms

a(0) =1a(1) =2047a(2) =177148a(3) =4192255a(4) =48828126a(5) =362621956a(6) =1977326744a(7) =8585738239a(8) =31381236757a(9) =99951173922a(10) =285311670612a(11) =742649588740