OFFSET
1,2
COMMENTS
The sequence is conjectured to be a permutation of A091072.
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..65537
PROG
(Scheme, with defineperm1-macro from Antti Karttunen's IntSeq-library)
(defineperm1 (A269361 n) (cond ((= 1 n) n) (else (let ((prev (A269361 (- n 1)))) (let loop ((k 1)) (cond ((and (not-lte? (A269361inv_cache k) (- n 1)) (isa003714? (* k prev))) k) (else (loop (+ 1 k)))))))))
(define (A269361inv_cache n) (A269361 (- n)))
;; We consider a > b (i.e. not less than b) also in case a is #f.
;; (Because of the stateful caching system used by defineperm1-macro):
(define (not-lte? a b) (cond ((not (number? a)) #t) (else (> a b))))
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Antti Karttunen, Feb 25 2016
STATUS
approved