A083534 - OEIS

%I #9 Nov 26 2015 08:52:46

%S 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,

%T 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,

%U 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

%N First difference sequence of A007617. Difference between consecutive values not being in the range of phi[A000010].

%H Reinhard Zumkeller, <a href="/A083534/b083534.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n)=A007617[n+1]-A007617[n]

%e a(n) is either 2 or 1 since odd numbers are in A007619;

%e if a(n)=1 then A007619[n+1] is an even number not in

%e range of phi; n={11,13,14,15,17} are not in the range of

%e phi and the corresponding differences are {2,1,1,2}.

%t 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]

%o (Haskell)

%o a083534 n = a083534_list !! (n-1)

%o a083534_list = zipWith (-) (tail a007617_list) a007617_list

%o -- _Reinhard Zumkeller_, Nov 26 2015

%Y Cf. A000010, A007617, A002202, A005277, A083531-A083536, A005277.

%K nonn

%O 1,1

%A _Labos Elemer_, May 20 2003