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 A062771 Order of automorphism group of the group C_n X C_2 (where C_n is the cyclic group with n elements). 3
 1, 6, 2, 8, 4, 12, 6, 16, 6, 24, 10, 16, 12, 36, 8, 32, 16, 36, 18, 32, 12, 60, 22, 32, 20, 72, 18, 48, 28, 48, 30, 64, 20, 96, 24, 48, 36, 108, 24, 64, 40, 72, 42, 80, 24, 132, 46, 64, 42, 120, 32, 96, 52, 108, 40, 96, 36, 168, 58, 64, 60, 180, 36, 128, 48, 120, 66, 128, 44 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Multiplicative with a(2) = 6, a(2^e) = 2^(e+1), e>1, a(p^e) = (p-1)*p^(e-1), p>2. - Christian G. Bower, May 18 2005 LINKS David A. Corneth, Table of n, a(n) for n = 1..10000 FORMULA For odd n: a(n) = phi(n) (sequence A000010). Conjecture: a(n) = 6*phi(n) if n mod 4 = 2 and a(n) = 4*phi(n) if n mod 4 = 0. - Vladeta Jovovic, Jul 20 2001 Conjecture confirmed. - Christian G. Bower, May 20 2005 MATHEMATICA a[n_] := Switch[Mod[n, 4], 0, 4, 2, 6, _, 1]*EulerPhi[n]; Array[a, 69] (* Jean-François Alcover, Apr 19 2018 *) PROG (PARI) a(n)=my(p=eulerphi(n)); if(n%2==1, p, if(n%4==2, 6*p, 4*p)); \\ Joerg Arndt, Sep 09 2020 CROSSREFS Cf. A000010. Sequence in context: A082577 A098686 A079718 * A249919 A254868 A071874 Adjacent sequences:  A062768 A062769 A062770 * A062772 A062773 A062774 KEYWORD nonn,easy,mult AUTHOR Ahmed Fares (ahmedfares(AT)my-deja.com), Jul 18 2001 EXTENSIONS More terms from Christian G. Bower, May 20 2005 STATUS approved

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Last modified May 11 03:49 EDT 2021. Contains 343784 sequences. (Running on oeis4.)