I was blind but now I see, what an elegant sequence.
(define (hofstadter n)
(letrec ((H (lambda (i R S)
(cond ((zero? i) (car R))
((member S R)
(H (- i 1) (cons (+ (car R) S 1) R) (+ S 2)))
(else (H (- i 1) (cons (+ (car R) S) R) (+ S 1)))))))
(H (sub1 n) '(1) 2)))
(map (lambda (e) (hofstadter (expt 10 e))) '(0 1 2 3 4))
=> (1 69 5764 526334 50874761)
;; (1 69 5764 526334 50874761)