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 A007614 All values attained by the phi(n) function, in ascending order. 12
 1, 1, 2, 2, 2, 4, 4, 4, 4, 6, 6, 6, 6, 8, 8, 8, 8, 8, 10, 10, 12, 12, 12, 12, 12, 12, 16, 16, 16, 16, 16, 16, 18, 18, 18, 18, 20, 20, 20, 20, 20, 22, 22, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 28, 28, 30, 30, 32, 32, 32, 32, 32, 32, 32, 36, 36, 36, 36, 36, 36, 36, 36 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Write down phi(1), phi(2), phi(3), ..., then sort this list. Of course the list before sorting is simply sequence A000010. To ensure that all terms are found, the values of phi(n) should be computed for all n up to a primorial p# -- which are the local minima of the phi function. Selecting and sorting the values of phi(n) <= phi(p#) produces the terms of this sequence. - T. D. Noe, Mar 22 2011 A002202(n) occurs A058277(n) times. - Reinhard Zumkeller, Nov 22 2015 LINKS Zak Seidov, Table of n, a(n) for n=1..9999 (values up to 5152) MATHEMATICA Cases[Sort[Table[EulerPhi[n], {n, 1, 36^2}]], n_ /; n<=36 ]  (* Jean-François Alcover, Mar 22 2011 *) A007614[m_]:=Select[Sort[Table[EulerPhi[n], {n, Prime[m]}]], #≤m&]; A007614[1000] (* Zak Seidov, Mar 22 2011 *) primorial = Times @@ Prime[Range[4]]; phi = EulerPhi[primorial]; Sort[Select[EulerPhi[Range[primorial]], # <= phi &]] (* T. D. Noe, Mar 22 2011 *) PROG (PARI)  (See A032447). (Haskell) import Data.List.Ordered (insertBag) a007614 n = a007614_list !! (n-1) a007614_list = f [1..] a002110_list [] where    f xs'@(x:xs) ps'@(p:ps) us      | x < p = f xs ps' \$ insertBag (a000010' x) us      | otherwise = vs ++ f xs' ps ws      where (vs, ws) = span (<= a000010' x) us -- Reinhard Zumkeller, Nov 22 2015 CROSSREFS Corresponding values of n are given by A032447. Cf. A000010. Cf. A002110, A002202, A058277 (run lengths). Sequence in context: A305117 A283426 A317841 * A289256 A287155 A287654 Adjacent sequences:  A007611 A007612 A007613 * A007615 A007616 A007617 KEYWORD nonn,easy,nice AUTHOR STATUS approved

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Last modified June 5 23:10 EDT 2020. Contains 334858 sequences. (Running on oeis4.)