a(1) = 1; a(n) = -Sum_{k=2..n} k^3 * a(floor(n/k)).

Terms

a(0) =1a(1) =-8a(2) =-35a(3) =-27a(4) =-152a(5) =91a(6) =-252a(7) =-252a(8) =-252a(9) =873a(10) =-458a(11) =-674a(12) =-2871a(13) =216a(14) =3591a(15) =3591a(16) =-1322a(17) =-1322a(18) =-8181a(19) =-9181a(20) =80a(21) =12059a(22) =-108a(23) =-108a(24) =-108a(25) =19665a(26) =19665a(27) =16921a(28) =-7468a(29) =-37843