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A057635 a(n) is the largest m such that phi(m)=n, where phi is Euler's Totient function. 7
2, 6, 0, 12, 0, 18, 0, 30, 0, 22, 0, 42, 0, 0, 0, 60, 0, 54, 0, 66, 0, 46, 0, 90, 0, 0, 0, 58, 0, 62, 0, 120, 0, 0, 0, 126, 0, 0, 0, 150, 0, 98, 0, 138, 0, 94, 0, 210, 0, 0, 0, 106, 0, 162, 0, 174, 0, 118, 0, 198, 0, 0, 0, 240, 0, 134, 0, 0, 0, 142, 0, 270, 0, 0, 0, 0, 0, 158, 0, 330, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

To check that a property P holds for all EulerPhi(x) not exceeding n, for n with a(n) > 0, it suffices to check P for all EulerPhi(x) with x not exceeding a(n). - Joseph L. Pe, Jan 10 2002

The Alekseyev link in A131883 establishes the following explicit relationship between A131883, A036912 and A057635. Namely, for t belonging to A036912, we have t=A131883(A057635(t)-1). In other words, A036912(n) = A131883(A057635(A036912(n))-1) for all n.

LINKS

T. D. Noe, Table of n, a(n) for n = 1..10000

EXAMPLE

m=12 is the largest value of m such that phi(m)=4, so a(4)=12.

MATHEMATICA

a(2n+1) = 0 for n > 0 and when a(2n) = 0, the Nontotients (A005277)/2 a = Table[0, {100}]; Do[ t = EulerPhi[n]; If[t < 101, a[[t]] = n], {n, 1, 10^6}]; a

CROSSREFS

Cf. A000010, A014197.

Sequence in context: A180314 A065344 A131105 * A269943 A243015 A139717

Adjacent sequences:  A057632 A057633 A057634 * A057636 A057637 A057638

KEYWORD

nonn

AUTHOR

Jud McCranie, Oct 10 2000

STATUS

approved

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Last modified September 26 10:59 EDT 2017. Contains 292518 sequences.