a(n) = floor(f(n)), where f(n) = n^4*(15-24*n+10*n^2) + 20*n^5*(1-n)^3 / (1-2*n(1-n)).

Terms

a(0) =0a(1) =1a(2) =-16a(3) =-318a(4) =-1895a(5) =-6936a(6) =-19313a(7) =-45055a(8) =-92831a(9) =-174433a(10) =-305249a(11) =-504751a(12) =-796967a(13) =-1210969a(14) =-1781345a(15) =-2548687a(16) =-3560063a(17) =-4869505a(18) =-6538481a(19) =-8636383a(20) =-11240999a(21) =-14439001a(22) =-18326417a(23) =-23009119a(24) =-28603295a(25) =-35235937a(26) =-43045313a(27) =-52181455a(28) =-62806631a(29) =-75095833