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A053098 When the Euler phi function is iterated with initial value A002110(n)=primorial, a(n)= first (maximal) power of 2 emerging during iteration. 0
2, 2, 8, 16, 128, 512, 8192, 16384, 262144, 2097152, 16777216, 67108864, 2147483648, 8589934592, 274877906944, 4398046511104, 70368744177664, 1125899906842624, 18014398509481984, 288230376151711744 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Analogous to A053047 (the same with a similar large initial value, n!)

LINKS

Table of n, a(n) for n=1..20.

EXAMPLE

n=6, A002110(6)=30030; the corresponding iteration chain is: {30030,5760,1536,512,256,128,64,32,16,8,4,2,1}. The first power of 2 is the 4th item after 3 iterations. It is 512, therefore a(6)=512.

CROSSREFS

Cf. A000010, A002110.

Sequence in context: A085542 A239682 A009725 * A194588 A175395 A169888

Adjacent sequences:  A053095 A053096 A053097 * A053099 A053100 A053101

KEYWORD

nonn

AUTHOR

Labos Elemer, Feb 28 2000

STATUS

approved

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Last modified February 20 12:33 EST 2018. Contains 299379 sequences. (Running on oeis4.)