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 A083534 First difference sequence of A007617. Difference between consecutive values not being in the range of phi[A000010]. 5
 2, 2, 2, 2, 2, 1, 1, 2, 2, 2, 2, 2, 1, 1, 2, 2, 2, 1, 1, 2, 1, 1, 2, 2, 2, 2, 2, 1, 1, 2, 2, 2, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 1, 1, 2, 2, 2, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 2, 2, 2, 2, 2, 2, 1, 1, 2, 1, 1, 2, 1, 1, 1, 1, 2, 2, 2, 2, 1, 1, 2, 2, 2, 1, 1, 2, 1, 1, 2, 2, 1, 1, 1, 1, 2, 1, 1, 2, 2, 2, 2 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 FORMULA a(n)=A007617[n+1]-A007617[n] EXAMPLE a(n) is either 2 or 1 since odd numbers are in A007619; if a(n)=1 then A007619[n+1] is an even number not in range of phi; n={11,13,14,15,17} are not in the range of phi and the corresponding differences are {2,1,1,2}. MATHEMATICA t0[x_] := Table[j, {j, 1, x}] t=Table[EulerPhi[w], {w, 1, 10000}]; u=Union[%]; c=Complement[t0[10000], u]; Delete[c-RotateRight[c], 1] PROG (Haskell) a083534 n = a083534_list !! (n-1) a083534_list = zipWith (-) (tail a007617_list) a007617_list -- Reinhard Zumkeller, Nov 26 2015 CROSSREFS Cf. A000010, A007617, A002202, A005277, A083531-A083536, A005277. Sequence in context: A237348 A037813 A159700 * A174664 A027386 A102300 Adjacent sequences:  A083531 A083532 A083533 * A083535 A083536 A083537 KEYWORD nonn AUTHOR Labos Elemer, May 20 2003 STATUS approved

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Last modified June 28 10:59 EDT 2022. Contains 354904 sequences. (Running on oeis4.)