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A080400 Largest squarefree number dividing phi of n. 5
1, 1, 2, 2, 2, 2, 6, 2, 6, 2, 10, 2, 6, 6, 2, 2, 2, 6, 6, 2, 6, 10, 22, 2, 10, 6, 6, 6, 14, 2, 30, 2, 10, 2, 6, 6, 6, 6, 6, 2, 10, 6, 42, 10, 6, 22, 46, 2, 42, 10, 2, 6, 26, 6, 10, 6, 6, 14, 58, 2, 30, 30, 6, 2, 6, 10, 66, 2, 22, 6, 70, 6, 6, 6, 10, 6, 30, 6, 78, 2, 6, 10, 82, 6, 2, 42, 14, 10, 22 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Also largest squarefree number dividing Carmichael's lambda, A002322(n). - Antti Karttunen, Jul 17 2017

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..16384

FORMULA

a(n) = A007947(A000010(n)).

a(n) = A007947(A002322(n)). - Antti Karttunen, Jul 17 2017

EXAMPLE

a(m * n) = A007947(a(m) * a(n)) if gcd(m, n) = 1. - David A. Corneth, Jul 16 2017

MATHEMATICA

Table[Max[Select[Divisors[EulerPhi[n]], SquareFreeQ]], {n, 90}] (* Harvey P. Dale, Jul 05 2012 *)

PROG

(PARI) A080400(n) = factorback(factorint(eulerphi(n))[, 1]); \\ Antti Karttunen & David A. Corneth, Jul 16 2017

CROSSREFS

Cf. A000010, A002322, A007947, A034380, A289624.

Sequence in context: A261902 A163368 A151948 * A328236 A119462 A293221

Adjacent sequences:  A080397 A080398 A080399 * A080401 A080402 A080403

KEYWORD

nonn

AUTHOR

Labos Elemer, Mar 19 2003

STATUS

approved

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Last modified November 13 10:50 EST 2019. Contains 329093 sequences. (Running on oeis4.)