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A326889
a(1) = 1; thereafter a(n) = a(n-1) / phi(n) if phi(n) divides a(n-1), otherwise a(n) = a(n-1) * phi(n), where phi is the Euler phi-function A000010.
3
1, 1, 2, 1, 4, 2, 12, 3, 18, 72, 720, 180, 15, 90, 720, 90, 1440, 240, 4320, 540, 45, 450, 9900, 79200, 3960, 330, 5940, 495, 13860, 110880, 3696, 231, 4620, 73920, 3080, 36960, 1330560, 73920, 3080, 49280, 1232, 14784, 352, 7040, 168960, 7680, 353280, 22080
OFFSET
1,3
COMMENTS
This sequence has similarities with A008336 and with A008338.
LINKS
EXAMPLE
The first terms, alongside phi(n), are:
n a(n) phi(n)
-- ---- ------
1 1 1
2 1 1
3 2 2
4 1 2
5 4 4
6 2 2
7 12 6
8 3 4
9 18 6
10 72 4
PROG
(PARI) for (n=1, 48, print1 (v=if (n==1, 1, v%e=eulerphi(n), v*e, v/e) ", "))
CROSSREFS
See A327442 for an additive variant.
Sequence in context: A132280 A345734 A059970 * A309303 A245471 A352548
KEYWORD
nonn
AUTHOR
Rémy Sigrist, Sep 13 2019
STATUS
approved