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 A009223 a(n) = gcd(sigma(n), phi(n)). 19
 1, 1, 2, 1, 2, 2, 2, 1, 1, 2, 2, 4, 2, 6, 8, 1, 2, 3, 2, 2, 4, 2, 2, 4, 1, 6, 2, 4, 2, 8, 2, 1, 4, 2, 24, 1, 2, 6, 8, 2, 2, 12, 2, 4, 6, 2, 2, 4, 3, 1, 8, 2, 2, 6, 8, 24, 4, 2, 2, 8, 2, 6, 4, 1, 12, 4, 2, 2, 4, 24, 2, 3, 2, 6, 4, 4, 12, 24, 2, 2, 1, 2, 2, 8, 4, 6, 8, 20, 2, 6, 8, 4, 4, 2, 24, 4, 2, 3, 12, 1, 2, 8 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS a(n) = gcd(A000203(n),A000010(n)). LINKS Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 MATHEMATICA Table[GCD[DivisorSigma[1, n], EulerPhi[n]], {n, 110}] (* Harvey P. Dale, Aug 10 2011 *) PROG (PARI) a(n)=gcd(sigma(n=factor(n)), eulerphi(n)) \\ Charles R Greathouse IV, Nov 27 2013 (Haskell) a009223 n = gcd (a000203 n) (a000010 n) -- Reinhard Zumkeller, Jan 19 2014 CROSSREFS Sequence in context: A082064 A082055 A073812 * A110244 A309020 A278495 Adjacent sequences:  A009220 A009221 A009222 * A009224 A009225 A009226 KEYWORD nonn AUTHOR STATUS approved

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Last modified December 13 12:37 EST 2019. Contains 329968 sequences. (Running on oeis4.)