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A353678
a(n) = 1 if the ratio of Euler totient phi to Carmichael's lambda function is 2, otherwise 0.
2
0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 0, 1, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0, 1, 0, 0, 0, 1, 1, 0
OFFSET
1
FORMULA
a(n) = 1 if A034380(n) [= A000010(n)/A002322(n)] is 2, otherwise 0.
a(n) >= A353677(n).
PROG
(PARI) A353678(n) = (2==(eulerphi(n)/lcm(znstar(n)[2])));
CROSSREFS
Characteristic function of A062373.
Cf. also A211487 (analogous sequence for ratio == 1, when n > 1).
Sequence in context: A101605 A358753 A175854 * A135133 A011712 A011715
KEYWORD
nonn
AUTHOR
Antti Karttunen, May 03 2022
STATUS
approved