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A277330
a(0)=1, a(1)=2, a(2n) = A003961(a(n)), a(2n+1) = lcm(a(n),a(n+1))/gcd(a(n),a(n+1)).
12
1, 2, 3, 6, 5, 2, 15, 30, 7, 10, 3, 30, 35, 2, 105, 210, 11, 70, 21, 30, 5, 10, 105, 42, 77, 70, 3, 210, 385, 2, 1155, 2310, 13, 770, 231, 30, 55, 70, 105, 6, 7, 2, 21, 42, 385, 10, 165, 66, 143, 110, 231, 210, 5, 70, 1155, 66, 1001, 770, 3, 2310, 5005, 2, 15015, 30030, 17, 10010, 3003, 30, 715, 770, 105, 66, 91, 154, 231, 6, 385, 70, 15, 42, 11, 14, 3, 42, 55, 2
OFFSET
0,2
COMMENTS
Each term is a squarefree number, A005117.
LINKS
FORMULA
a(0) = 1, a(1) = 2, a(2n) = A003961(a(n)), a(2n+1) = lcm(a(n),a(n+1))/gcd(a(n),a(n+1)).
Other identities. For all n >= 0:
a(n) = A007913(A260443(n)).
a(n) = A019565(A264977(n)), A048675(a(n)) = A264977(n).
A055396(a(n)) = A277707(A260443(n)) = A001511(n).
PROG
(Scheme, with memoization-macro definec)
(definec (A277330 n) (cond ((<= n 1) (+ 1 n)) ((even? n) (A003961 (A277330 (/ n 2)))) (else (/ (lcm (A277330 (/ (- n 1) 2)) (A277330 (/ (+ n 1) 2))) (gcd (A277330 (/ (- n 1) 2)) (A277330 (/ (+ n 1) 2)))))))
CROSSREFS
Cf. A023758 (positions where coincides with A260443).
Cf. A277701, A277712, A277713 for the positions of 2's, 3's and 6's in this sequence, which are also the first three rows of array A277710.
Cf. also A255483.
Sequence in context: A359623 A091556 A299207 * A072298 A130686 A213927
KEYWORD
nonn
AUTHOR
Antti Karttunen, Oct 27 2016
STATUS
approved