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A280696 Largest Lucas proper divisor of n, a(1) = a(2) = 1. 5
1, 1, 1, 2, 1, 3, 1, 4, 3, 2, 1, 4, 1, 7, 3, 4, 1, 3, 1, 4, 7, 11, 1, 4, 1, 2, 3, 7, 1, 3, 1, 4, 11, 2, 7, 18, 1, 2, 3, 4, 1, 7, 1, 11, 3, 2, 1, 4, 7, 2, 3, 4, 1, 18, 11, 7, 3, 29, 1, 4, 1, 2, 7, 4, 1, 11, 1, 4, 3, 7, 1, 18, 1, 2, 3, 4, 11, 3, 1, 4, 3, 2, 1, 7, 1, 2, 29, 11, 1, 18, 7, 4, 3, 47, 1, 4, 1, 7, 11, 4, 1, 3, 1, 4, 7, 2, 1, 18, 1, 11, 3, 7, 1, 3, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,4
COMMENTS
For n > 1, a(n) = greatest Lucas number (A000032) that divides n and is less than n.
LINKS
FORMULA
a(n) = n / A280697(n).
Other identities. For all n >= 1:
a(A057854(n)) = A280694(A057854(n)).
a(A000204(n)) = A280698(n).
PROG
(Scheme)
;; A stand-alone program:
(define (A280696 n) (let loop ((l1 1) (l2 3) (lpd 1)) (cond ((>= l1 n) (if (and (= 1 lpd) (even? n) (> n 2)) 2 lpd)) ((zero? (modulo n l1)) (loop l2 (+ l1 l2) l1)) (else (loop l2 (+ l1 l2) lpd)))))
CROSSREFS
Cf. A057854 (gives the positions n > 1 where this sequence and A280694 obtain equal values).
Sequence in context: A032451 A214494 A088445 * A293247 A020653 A094522
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jan 11 2017
STATUS
approved

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Last modified March 28 20:05 EDT 2024. Contains 371254 sequences. (Running on oeis4.)