a(n) = 1 + Sum_{k=2..n} (-1)^k * k^2 * a(floor(n/k)).

Terms

a(0) =1a(1) =5a(2) =-4a(3) =28a(4) =3a(5) =-33a(6) =-82a(7) =174a(8) =174a(9) =74a(10) =-47a(11) =-335a(12) =-504a(13) =-700a(14) =-475a(15) =1573a(16) =1284a(17) =1284a(18) =923a(19) =123a(20) =564a(21) =80a(22) =-449a(23) =-2753a(24) =-2753a(25) =-3429a(26) =-3429a(27) =-4997a(28) =-5838a(29) =-4938