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 A049586 a(n) is the GCD of the cototients (A051953) of n and n+1. 6
 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 5, 3, 1, 1, 1, 1, 3, 3, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 5, 1, 1, 1, 1, 3, 3, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 3, 3, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 3 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,9 COMMENTS Most of the terms are 1. LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..5000 FORMULA a(n) = gcd(n + 1 - phi(n+1), n - phi(n)). a(n) = gcd(A051953(n+1), A051953(n)). MATHEMATICA Map[GCD @@ Map[# - EulerPhi@ # &, #] &, Partition[Range@ 106, 2, 1]] (* Michael De Vlieger, Aug 09 2017 *) PROG (Magma) [GCD((n+1-EulerPhi(n+1)), n-EulerPhi(n)): n in [1..100]]; // Vincenzo Librandi, Aug 10 2017 CROSSREFS Cf. A000010, A051953, A058515. Sequence in context: A070670 A368472 A368711 * A342466 A133721 A083202 Adjacent sequences: A049583 A049584 A049585 * A049587 A049588 A049589 KEYWORD nonn AUTHOR Labos Elemer, Dec 28 2000 STATUS approved

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Last modified February 25 13:12 EST 2024. Contains 370330 sequences. (Running on oeis4.)