a(n) = phi(n^3 + n^2 + n + 1).

Terms

a(0) =1a(1) =2a(2) =8a(3) =16a(4) =64a(5) =48a(6) =216a(7) =160a(8) =288a(9) =320a(10) =1000a(11) =480a(12) =1344a(13) =768a(14) =1568a(15) =1792a(16) =4096a(17) =1344a(18) =4320a(19) =2880a(20) =4800a(21) =3840a(22) =8448a(23) =3328a(24) =11520a(25) =7488a(26) =12168a(27) =6912a(28) =17472a(29) =6720