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)).

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

Antti Karttunen, Table of n, a(n) for n = 0..8191

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. A001511, A003961, A005117, A007913, A019565, A048675, A055396, A260443, A264977, A277707.

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

Adjacent sequences: A277327 A277328 A277329 * A277331 A277332 A277333

Keyword

nonn

Author

Antti Karttunen, Oct 27 2016

Status

approved