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A277328 Number of primes (counted with multiplicity) dividing gcd(A260443(n), A260443(n+1)): a(n) = A001222(A277198(n)). 7
0, 0, 1, 0, 0, 1, 2, 0, 0, 2, 2, 1, 1, 2, 3, 0, 0, 3, 3, 1, 1, 4, 4, 1, 1, 4, 4, 2, 2, 3, 4, 0, 0, 4, 4, 3, 2, 5, 6, 1, 1, 7, 6, 2, 3, 6, 6, 1, 1, 6, 6, 3, 3, 7, 7, 2, 2, 6, 6, 3, 3, 4, 5, 0, 0, 5, 5, 4, 4, 8, 8, 2, 2, 9, 9, 4, 4, 8, 9, 1, 1, 10, 9, 5, 5, 10, 11, 2, 2, 11, 10, 5, 6, 8, 8, 1, 1, 8, 8, 5, 4, 10, 11, 3, 3, 12 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,7

LINKS

Antti Karttunen, Table of n, a(n) for n = 0..8192

FORMULA

a(n) = A001222(A277198(n)).

a(n) >= A277327(n).

PROG

(Scheme)

(define (A277328 n) (A001222 (A277198 n)))

;; A standalone implementation:

(define (A277328 n) (reduce + 0 (gcd_of_exp_lists (A260443as_coeff_list n) (A260443as_coeff_list (+ 1 n)))))

(definec (A260443as_coeff_list n) (cond ((zero? n) (list)) ((= 1 n) (list 1)) ((even? n) (cons 0 (A260443as_coeff_list (/ n 2)))) (else (add_two_lists (A260443as_coeff_list (/ (- n 1) 2)) (A260443as_coeff_list (/ (+ n 1) 2))))))

(define (add_two_lists nums1 nums2) (let ((len1 (length nums1)) (len2 (length nums2))) (cond ((< len1 len2) (add_two_lists nums2 nums1)) (else (map + nums1 (append nums2 (make-list (- len1 len2) 0)))))))

(define (gcd_of_exp_lists nums1 nums2) (let ((len1 (length nums1)) (len2 (length nums2))) (cond ((< len1 len2) (gcd_of_exp_lists nums2 nums1)) (else (map min nums1 (append nums2 (make-list (- len1 len2) 0)))))))

CROSSREFS

Cf. A001222, A125184, A260443, A277198, A277327.

Sequence in context: A146165 A308831 A277327 * A318178 A283307 A273514

Adjacent sequences:  A277325 A277326 A277327 * A277329 A277330 A277331

KEYWORD

nonn,look

AUTHOR

Antti Karttunen, Oct 13 2016

STATUS

approved

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Last modified November 22 18:55 EST 2019. Contains 329410 sequences. (Running on oeis4.)