A277326 - OEIS

A277326

LCM of nonzero coefficients of the n-th Stern polynomial.

1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 2, 3, 1, 2, 1, 1, 1, 2, 2, 3, 2, 12, 3, 6, 1, 6, 2, 3, 1, 2, 1, 1, 1, 2, 2, 6, 2, 20, 3, 12, 2, 4, 12, 30, 3, 20, 6, 6, 1, 6, 6, 15, 2, 60, 3, 12, 1, 6, 2, 3, 1, 2, 1, 1, 1, 2, 2, 6, 2, 60, 6, 12, 2, 12, 20, 40, 3, 140, 12, 12, 2, 12, 4, 40, 12, 60, 30, 140, 3, 60, 20, 40, 6, 20, 6, 6, 1

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OFFSET

0,6

COMMENTS

a(n) = the least common multiple of nonzero terms on the n-th row of A125184.

LINKS

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

Index entries for sequences related to lcm's

FORMULA

a(n) = A072411(A260443(n)).

a(2n) = a(n).

a(n) <= A277325(n).

PROG

(Scheme)

(define (A277326 n) (A072411 (A260443 n)))

;; A standalone implementation:

(define (A277326 n) (reduce lcm 1 (filter positive? (A260443as_coeff_list 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)))))))

CROSSREFS

Cf. A072411, A125184, A260443.

Differs from A277325 for the first time at n=13, where a(13) = 2, while A277325(13) = 4.

After n=0, differs from A277315 for the first time at n=21, where a(21) = 12, while A277315(21) = 4.

Sequence in context: A262561 A264990 A277315 * A380528 A050431 A051574

Adjacent sequences: A277323 A277324 A277325 * A277327 A277328 A277329

KEYWORD

nonn

AUTHOR

Antti Karttunen, Oct 13 2016

STATUS

approved