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 A217863 a(n) = phi(lcm(1,2,3,...,n)), where phi is Euler's totient function. 3

%I

%S 1,1,2,4,16,16,96,192,576,576,5760,5760,69120,69120,69120,138240,

%T 2211840,2211840,39813120,39813120,39813120,39813120,875888640,

%U 875888640,4379443200,4379443200,13138329600,13138329600,367873228800,367873228800,11036196864000

%N a(n) = phi(lcm(1,2,3,...,n)), where phi is Euler's totient function.

%C This is a composition f(g(x)). g(x) = lcm(1...x) and f(x) = phi(x), Euler's totient function. The sequence generated is the number of prime congruence classes (prime spokes) for wheel factorization in mod g(x).

%C First column of A096180. - _Eric Desbiaux_, Apr 23 2013

%H Reinhard Zumkeller, <a href="/A217863/b217863.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = A000010(A003418(n)). - _Omar E. Pol_, Nov 25 2012

%t EulerPhi[Table[LCM @@ Range[n], {n, 35}]] (* _T. D. Noe_, Oct 16 2012 *)

%o (Haskell)

%o a217863 = a000010 . a003418 -- _Reinhard Zumkeller_, Nov 24 2012

%o (PARI) a(n) = eulerphi(lcm(vector(n, k, k))); \\ _Michel Marcus_, Aug 25 2015

%Y Cf. A000010 (Euler phi), A003418 (LCM).

%K nonn,easy

%O 1,3

%A _Joshua S.M. Weiner_, Oct 13 2012

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Last modified January 18 21:54 EST 2019. Contains 319282 sequences. (Running on oeis4.)