Final digit of 3^n.

Terms

a(0) =1a(1) =3a(2) =9a(3) =7a(4) =1a(5) =3a(6) =9a(7) =7a(8) =1a(9) =3a(10) =9a(11) =7a(12) =1a(13) =3a(14) =9a(15) =7a(16) =1a(17) =3a(18) =9a(19) =7a(20) =1a(21) =3a(22) =9a(23) =7a(24) =1a(25) =3a(26) =9a(27) =7a(28) =1a(29) =3