The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A217863 a(n) = phi(lcm(1,2,3,...,n)), where phi is Euler's totient function. 4
 1, 1, 2, 4, 16, 16, 96, 192, 576, 576, 5760, 5760, 69120, 69120, 69120, 138240, 2211840, 2211840, 39813120, 39813120, 39813120, 39813120, 875888640, 875888640, 4379443200, 4379443200, 13138329600, 13138329600, 367873228800, 367873228800, 11036196864000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS 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). First column of A096180. - Eric Desbiaux, Apr 23 2013 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..1000 FORMULA a(n) = A000010(A003418(n)). - Omar E. Pol, Nov 25 2012 From Peter Bala, Feb 19 2019: (Start) a(n) = Product_{k = 1..n} A072211(k). With p denoting a prime, a(n) = ( Product_{p <= n} (p - 1) ) * ( Product_{p^2 <= n} p ) * ( Product_{p^3 <= n} p ) * ... . For example, a(16) = ((2-1)*(3-1)*(5-1)*(7-1)*(11-1)*(13-1)) * (2*3) * 2 * 2 = 138240. (End) MAPLE with(numtheory): a:=n->phi(lcm(seq(m, m=1..n))): seq(a(n), n=1..40); # Muniru A Asiru, Feb 20 2019 MATHEMATICA EulerPhi[Table[LCM @@ Range[n], {n, 35}]] (* T. D. Noe, Oct 16 2012 *) PROG (Haskell) a217863 = a000010 . a003418 -- Reinhard Zumkeller, Nov 24 2012 (PARI) a(n) = eulerphi(lcm(vector(n, k, k))); \\ Michel Marcus, Aug 25 2015 CROSSREFS Cf. A000010 (Euler phi), A003418 (LCM), A072211, A173557. Sequence in context: A370874 A337109 A210579 * A186108 A131560 A067709 Adjacent sequences: A217860 A217861 A217862 * A217864 A217865 A217866 KEYWORD nonn,easy AUTHOR Joshua S.M. Weiner, Oct 13 2012 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 27 08:06 EDT 2024. Contains 372850 sequences. (Running on oeis4.)