

A181660


Numbers at which the sum of the iterated totient function (A092693) attains a minimum.


2



1, 2, 6, 12, 18, 30, 42, 54, 60, 66, 90, 126, 150, 210, 270, 294, 330, 420, 462, 630, 660, 840, 882, 1050, 1260, 1470, 1680, 1890, 2310, 2730, 2940, 3150, 3234, 3570, 3990, 4410, 4620, 4830, 5250, 5460, 5670, 6090, 6930, 7350, 8190, 9030, 9240, 9450, 9660
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OFFSET

1,2


COMMENTS

That is, for each n in this sequence, A092693(n) < A092693(m) for m > n. Do all primorials appear here?


LINKS

T. D. Noe, Table of n, a(n) for n=1..300


MATHEMATICA

kMax=2*3*5*7*11*13; t=Table[0, {kMax}]; Do[e=EulerPhi[k]; t[[k]]=e+t[[e]], {k, 2, kMax}]; mn=Infinity; Reverse[Reap[Do[If[t[[ k]]<mn, mn=t[[ k]]; Sow[kMaxk+1]], {k, kMax}]][[2, 1]]]


CROSSREFS

Cf. A181659
Sequence in context: A006511 A325708 A113274 * A036913 A317089 A117311
Adjacent sequences: A181657 A181658 A181659 * A181661 A181662 A181663


KEYWORD

nonn


AUTHOR

T. D. Noe, Nov 04 2010


STATUS

approved



