Fixed point of "k -> k/2 or (k-1)/2 until result is prime", starting with prime(n)-1.

Terms

a(0) =1a(1) =2a(2) =2a(3) =3a(4) =5a(5) =3a(6) =2a(7) =2a(8) =11a(9) =7a(10) =7a(11) =2a(12) =5a(13) =5a(14) =23a(15) =13a(16) =29a(17) =7a(18) =2a(19) =17a(20) =2a(21) =19a(22) =41a(23) =11a(24) =3a(25) =3a(26) =3a(27) =53a(28) =13a(29) =7