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 A286266 Number of totient abundant numbers <= 10^n. 0

%I

%S 2,36,383,3708,35731,347505,3407290,33579303

%N Number of totient abundant numbers <= 10^n.

%C Totient abundant numbers are defined in A286265.

%C a(3)-a(8) were calculated by Loomis & Luca (2008).

%H Paul Loomis and Florian Luca, <a href="https://www.emis.de/journals/INTEGERS/papers/i6/i6.Abstract.html">On totient abundant numbers</a>, Electronic Journal of Combinatorial Number Theory, Vol. 8, #A06 (2008).

%e There are 2 totient abundant numbers <= 10^1 (5 and 7), thus a(1)=2.

%t Accumulate@ Table[Count[Select[Range[10^(n - 1) + 1, 10^n], (Total@ FixedPointList[EulerPhi, #] - (# + 1)) > # &], k_ /; k <= 10^n], {n, 6}] (* _Michael De Vlieger_, May 06 2017, after _Alonso del Arte_ at A092693 *)

%Y Cf. A000010, A082897, A092693, A286265.

%K nonn,more

%O 1,1

%A _Amiram Eldar_, May 05 2017

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Last modified August 14 01:00 EDT 2020. Contains 336473 sequences. (Running on oeis4.)