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A092694 Product of iterated phi(n). 3
1, 1, 2, 2, 8, 2, 12, 8, 12, 8, 80, 8, 96, 12, 64, 64, 1024, 12, 216, 64, 96, 80, 1760, 64, 1280, 96, 216, 96, 2688, 64, 1920, 1024, 1280, 1024, 1536, 96, 3456, 216, 1536, 1024, 40960, 96, 4032, 1280, 1536, 1760, 80960, 1024, 4032, 1280, 32768, 1536, 79872, 216 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

A logarithmic plot of this sequence shows an unusual banded structure.

LINKS

T. D. Noe, Table of n, a(n) for n=1..10000

T. D. Noe, Plot of A092694

FORMULA

a(1) = 1, a(n) = phi(n) * a(phi(n))

EXAMPLE

a(100) = 40960 because the iterations of phi (40, 16, 8, 4, 2, 1) have a product of 40960.

MATHEMATICA

nMax=100; a=Table[1, {nMax}]; Do[e=EulerPhi[n]; a[[n]]=e*a[[e]], {n, 2, nMax}]; a

PROG

(Haskell)

a092694 n = snd $ until ((== 1) . fst) f (a000010 n, 1) where

   f (x, p) = (a000010 x, p * x)

-- Reinhard Zumkeller, Jan 30 2014

CROSSREFS

Cf. A003434 (iterations of phi(n) needed to reach 1), A092693 (iterated phi sum).

Cf. A000010.

Sequence in context: A011147 A273168 A098818 * A098984 A088560 A222821

Adjacent sequences:  A092691 A092692 A092693 * A092695 A092696 A092697

KEYWORD

nonn,look

AUTHOR

T. D. Noe, Mar 04 2004

STATUS

approved

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Last modified October 21 20:44 EDT 2019. Contains 328315 sequences. (Running on oeis4.)