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 A058515 GCD of totients of consecutive integers. 10
 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 4, 6, 2, 8, 8, 2, 6, 2, 4, 2, 2, 2, 4, 4, 6, 6, 4, 4, 2, 2, 4, 4, 8, 12, 12, 18, 6, 8, 8, 4, 6, 2, 4, 2, 2, 2, 2, 2, 4, 8, 4, 2, 2, 8, 12, 4, 2, 2, 4, 30, 6, 4, 16, 4, 2, 2, 4, 4, 2, 2, 24, 36, 4, 4, 12, 12, 6, 2, 2, 2, 2, 2, 8, 2, 14, 8, 8, 8, 24, 4, 4, 2, 2, 8, 32, 6 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS Antti Karttunen, Table of n, a(n) for n = 1..10000 FORMULA a(n) = gcd(Phi(n+1), Phi(n)), where Phi = A000010. EXAMPLE n=61, gcd(Phi(62), Phi(61)) = gcd(30, 60) = 30, so a(61)=30. MATHEMATICA Map[GCD @@ # &, Partition[EulerPhi@ Range@ 98, 2, 1]] (* Michael De Vlieger, Aug 22 2017 *) PROG (PARI) a(n) = gcd(eulerphi(n), eulerphi(n+1)); \\ Michel Marcus, Dec 10 2013 CROSSREFS Cf. A000010, A049586, A060778. Sequence in context: A237975 A327343 A032574 * A126696 A244464 A250201 Adjacent sequences: A058512 A058513 A058514 * A058516 A058517 A058518 KEYWORD nonn AUTHOR Labos Elemer, Dec 21 2000 EXTENSIONS Offset corrected to 1 by Michel Marcus, Dec 10 2013 STATUS approved

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Last modified September 30 14:31 EDT 2023. Contains 365792 sequences. (Running on oeis4.)