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A355451
a(n) = 1 if n is even and phi(x) = n has no solutions, otherwise 0.
3
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0
OFFSET
1
FORMULA
a(n) = A059841(n) * (1-A264739(n));
For n > 2, a(n) >= A355452(n).
PROG
(PARI) A355451(n) = (!(n%2) && !istotient(n));
CROSSREFS
Characteristic function of A005277.
Sequence in context: A216038 A011728 A297043 * A133010 A234323 A162782
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jul 12 2022
STATUS
approved