Nested floor product of n and fractions (k+1)/k for all k>0 (mod 3), divided by 3.

Terms

a(0) =1a(1) =4a(2) =9a(3) =20a(4) =29a(5) =44a(6) =69a(7) =104a(8) =121a(9) =180a(10) =241a(11) =284a(12) =349a(13) =420a(14) =521a(15) =664a(16) =701a(17) =860a(18) =1009a(19) =1184a(20) =1301a(21) =1540a(22) =1789a(23) =1964a(24) =2181a(25) =2380a(26) =2701a(27) =3124a(28) =3301a(29) =3704