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A330273 Infinitary perfect totient numbers: numbers that equal to the sum of their iterated infinitary totient function (A091732). 4
3, 10, 21, 44, 93, 118, 170, 320, 548, 3596, 3620, 4772, 5564, 18260, 33051, 256425, 403700, 1071129, 1790160, 2318180, 3968852, 4027375, 10001319, 11270012, 12048740, 13358121, 31741593, 46271673, 56149161, 4344134553 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The infinitary version of A082897 (perfect totient numbers), in which the infinitary totient function iphi (A091732) replaces the Euler totient function (A000010).

LINKS

Table of n, a(n) for n=1..30.

EXAMPLE

10 is an infinitary perfect totient number because iphi(10) + iphi(iphi(10)) + ... = 4 + 3 + 2 + 1 = 10.

MATHEMATICA

f[p_, e_] := p^(2^(-1 + Position[Reverse @ IntegerDigits[e, 2], _?(# == 1 &)])); iphi[1] = 1; iphi[n_] := iphi[n] = Times @@ (Flatten@(f @@@ FactorInteger[n]) - 1); infPerfTotQ[n_] := Plus @@ FixedPointList[iphi@# &, n] == 2 n + 1; Select[Range[1000], infPerfTotQ]

CROSSREFS

Cf. A082897, A091732, A286067.

Sequence in context: A268348 A117495 A007687 * A335666 A192033 A295063

Adjacent sequences:  A330270 A330271 A330272 * A330274 A330275 A330276

KEYWORD

nonn,more

AUTHOR

Amiram Eldar, Dec 13 2019

STATUS

approved

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Last modified September 20 19:27 EDT 2021. Contains 347589 sequences. (Running on oeis4.)