

A060610


Repeatedly apply Euler phi to the nth prime; a(n) is the number of terms in the resulting iteration chain which are not powers of 2 (number of initial iterations until reaching the first power of 2).


0



0, 1, 1, 2, 2, 2, 1, 3, 3, 3, 2, 3, 2, 3, 4, 3, 4, 2, 3, 3, 3, 3, 3, 3, 2, 3, 2, 4, 4, 3, 4, 3, 2, 4, 4, 3, 3, 5, 4, 4, 4, 3, 4, 2, 4, 3, 3, 4, 4, 4, 4, 3, 2, 4, 1, 4, 4, 4, 4, 3, 5, 4, 3, 3, 3, 4, 3, 3, 5, 4, 3, 5, 3, 3, 5, 5, 3, 3, 3, 2, 4, 3, 4, 4, 4, 3, 3, 4, 4, 3, 5, 4, 6, 4, 4, 5, 5, 3, 4, 4, 4, 5, 4, 4, 4
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OFFSET

1,4


LINKS

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


FORMULA

a(n)=A049115[A000040(n)]


EXAMPLE

n=100,p(100)=541, Phiiteration chain is {541,540,144,48,16,8,4,2,1} with 9 terms. The first 4 terms (541,540,144,48) are not powers of 2, som a(100)=4.


MATHEMATICA

Table[Count[FixedPointList[EulerPhi[#]&, Prime[n]], _?(!IntegerQ[ Log[ 2, #]]&)], {n, 110}] (* Harvey P. Dale, Sep 18 2016 *)


CROSSREFS

Cf. A000040, A000010, A049108, A049113, A049116, A049115, A003434.
Sequence in context: A209266 A269400 A130267 * A017125 A063276 A055253
Adjacent sequences: A060607 A060608 A060609 * A060611 A060612 A060613


KEYWORD

easy,nonn


AUTHOR

Labos Elemer, Apr 13 2001


EXTENSIONS

Definition clarified by Harvey P. Dale, Sep 18 2016


STATUS

approved



