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A049225 Values of totient function applied to squarefree numbers; or numbers of form Product (p_i-1) where p_i are distinct primes. 2
1, 2, 4, 6, 8, 10, 12, 16, 18, 20, 22, 24, 28, 30, 32, 36, 40, 42, 44, 46, 48, 52, 56, 58, 60, 64, 66, 70, 72, 78, 80, 82, 84, 88, 92, 96, 100, 102, 104, 106, 108, 112, 116, 120, 126, 128, 130, 132, 136, 138, 140, 144, 148, 150, 156, 160, 162, 164, 166, 168, 172, 176 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..62.

Max Alekseyev, PARI scripts for various problems

FORMULA

Numbers n such that n = phi(k) and |mu(k)| = 1.

EXAMPLE

8,120,48 are here as totient functions of squarefree numbers 15, 143, 210. 54 and 110, 294, 342 are missing since there are no squarefree k such that phi(k) = 54, 110, etc.

PROG

(PARI) isok(n) = {my(v = invphi(n)); (#v) && (#select(x->issquarefree(x), v)); } \\ Michel Marcus, Feb 25 2019

CROSSREFS

Terms of A049200 after ordering and omitting multiple occurrences.

Cf. A000010, A005117, A013929, A002174, A002202, A049200.

Sequence in context: A049445 A002174 A002202 * A076450 A097379 A114871

Adjacent sequences:  A049222 A049223 A049224 * A049226 A049227 A049228

KEYWORD

nonn

AUTHOR

Labos Elemer

STATUS

approved

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Last modified July 8 04:16 EDT 2020. Contains 335504 sequences. (Running on oeis4.)