A353678 a(n) = 1 if the ratio of Euler totient phi to Carmichael's lambda function is 2, otherwise 0.

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

Links

Antti Karttunen, Table of n, a(n) for n = 1..65537

Index entries for characteristic functions

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. A000010, A002322, A034380, A353677.

Cf. also A211487 (analogous sequence for ratio == 1, when n > 1).

Sequence in context: A101605 A358753 A175854 * A135133 A011712 A011715

Adjacent sequences: A353675 A353676 A353677 * A353679 A353680 A353681

Keyword

nonn

Author

Antti Karttunen, May 03 2022

Status

approved