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 A053139 a(n) = phi(n) - mu(n). 1
 0, 2, 3, 2, 5, 1, 7, 4, 6, 3, 11, 4, 13, 5, 7, 8, 17, 6, 19, 8, 11, 9, 23, 8, 20, 11, 18, 12, 29, 9, 31, 16, 19, 15, 23, 12, 37, 17, 23, 16, 41, 13, 43, 20, 24, 21, 47, 16, 42, 20, 31, 24, 53, 18, 39, 24, 35, 27, 59, 16, 61, 29, 36, 32, 47, 21, 67, 32 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS G. C. Greubel, Table of n, a(n) for n = 1..10000 FORMULA a(n) = n if and only if n is a prime. MATHEMATICA a[ n_] := EulerPhi @ n - MoebiusMu @ n; Table[a[n], {n, 70}] (* Michael Somos, Jul 19 2011 *) PROG (PARI) {a(n) = if( n==0, 0, eulerphi( n) - moebius( n))} /* Michael Somos, Jul 19 2011 */ (MAGMA) [EulerPhi(n) - MoebiusMu(n): n in [1..100]]; // G. C. Greubel, Sep 03 2018 CROSSREFS Cf. A000010, A008683. Sequence in context: A332424 A293212 A157449 * A127705 A124386 A098668 Adjacent sequences:  A053136 A053137 A053138 * A053140 A053141 A053142 KEYWORD nonn AUTHOR N. J. A. Sloane, Mar 25 2000 STATUS approved

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Last modified September 23 21:27 EDT 2020. Contains 337315 sequences. (Running on oeis4.)