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A083534 First difference sequence of A007617. Difference between consecutive values not being in the range of phi[A000010]. 0
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

Table of n, a(n) for n=1..105.

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]

CROSSREFS

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

Sequence in context: A237348 A037813 A159700 * A174664 A102300 A202146

Adjacent sequences:  A083531 A083532 A083533 * A083535 A083536 A083537

KEYWORD

nonn

AUTHOR

Labos Elemer, May 20 2003

STATUS

approved

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Last modified September 23 18:22 EDT 2014. Contains 247183 sequences.