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A286266 Number of totient abundant numbers <= 10^n. 0
2, 36, 383, 3708, 35731, 347505, 3407290, 33579303 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Totient abundant numbers are defined in A286265.

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

LINKS

Table of n, a(n) for n=1..8.

Paul Loomis and Florian Luca, On totient abundant numbers, Electronic Journal of Combinatorial Number Theory, Vol. 8, #A06 (2008).

EXAMPLE

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

MATHEMATICA

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 *)

CROSSREFS

Cf. A000010, A082897, A092693, A286265.

Sequence in context: A119582 A157055 A057407 * A193127 A092852 A139738

Adjacent sequences:  A286263 A286264 A286265 * A286267 A286268 A286269

KEYWORD

nonn,more

AUTHOR

Amiram Eldar, May 05 2017

STATUS

approved

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Last modified July 14 09:22 EDT 2020. Contains 335720 sequences. (Running on oeis4.)