Take sum of squares of digits of previous term; start with 9.

Terms

a(0) =9a(1) =81a(2) =65a(3) =61a(4) =37a(5) =58a(6) =89a(7) =145a(8) =42a(9) =20a(10) =4a(11) =16a(12) =37a(13) =58a(14) =89a(15) =145a(16) =42a(17) =20a(18) =4a(19) =16a(20) =37a(21) =58a(22) =89a(23) =145a(24) =42a(25) =20a(26) =4a(27) =16a(28) =37a(29) =58