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A363371
a(n) is the least prime p for which (p-1)*phi(p^n) is a nontotient, where phi is the Euler totient function (A000010).
1
23, 11, 23, 11, 23, 11, 47, 11, 11, 23, 47, 23, 23, 23, 47, 47, 103, 103, 103, 103, 103, 103, 167, 103, 103, 103, 103, 103, 103, 103, 103, 103, 103, 179, 103, 103, 103, 103, 103, 103, 103, 103, 127, 103, 103, 103, 103, 103, 103, 103, 103, 103, 103, 127, 127, 103, 127, 127, 127
OFFSET
1,1
COMMENTS
Thus a(n) is the least prime p for which p-1=phi(p), a totient value, multiplied by phi(p^n), another totient value, gives a nontotient. There are several instances of these numbers in A361058.
LINKS
PROG
(PARI) a(n) = my(p=2); while (istotient((p-1)*eulerphi(p^n)), p = nextprime(p+1)); p;
CROSSREFS
Cf. A000010, A002202 (totient values) A005277 (nontotients), A361058.
Sequence in context: A128364 A281924 A054574 * A016837 A226218 A294087
KEYWORD
nonn
AUTHOR
Michel Marcus, May 29 2023
STATUS
approved