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A248815 Numbers equal to the arithmetic derivative of their Euler totient function. 1
31, 32, 80, 81, 112, 176, 192, 244, 368, 752, 859, 912, 944, 1296, 1328, 1712, 1723, 2672, 2864, 3024, 3632, 4208, 5552, 5744, 6128, 6156, 7472, 7664, 8048, 8748, 9008, 9392, 11504, 13424, 13808, 14192, 15728, 16304, 18992, 20412, 20528, 20912, 21104, 21872 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Solutions of the equation n = (phi(n))’.

LINKS

Paolo P. Lava, Table of n, a(n) for n = 1..500

EXAMPLE

Euler totient function of 32 is 16 and the arithmetic derivative of 16 is 32.

MAPLE

with(numtheory): P:= proc(q) local a, n, p; for n from 1 to q do

a:=phi(n)*add(op(2, p)/op(1, p), p=ifactors(phi(n))[2]);

if n=a then print(n); fi; od; end: P(10^9);

CROSSREFS

Cf. A000005, A003415, A166374.

Sequence in context: A042924 A042922 A171235 * A280647 A152045 A041479

Adjacent sequences:  A248812 A248813 A248814 * A248816 A248817 A248818

KEYWORD

nonn

AUTHOR

Paolo P. Lava, Oct 15 2014

STATUS

approved

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Last modified April 21 10:03 EDT 2019. Contains 322328 sequences. (Running on oeis4.)