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A252255 Numbers n such that sigma(Rev(phi(n))) = phi(Rev(sigma(n))), where sigma is the sum of divisors and phi the Euler totient function. 1
1, 14, 61, 966, 1428, 9174, 15642, 19934, 22155, 27075, 36650, 48731, 51095, 54184, 57902, 59711, 61039, 89276, 98645, 113080, 126850, 140283, 142149, 154670, 165822, 190908, 197705, 198712, 202096, 203107, 247268, 274368, 274716, 307836, 311925, 331037, 366740 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Paolo P. Lava, Table of n, a(n) for n = 1..100

EXAMPLE

phi(14) = 6, Rev(6) = 6 and sigma(6) = 12;

sigma(14) = 24, Rev(24) = 42 and sigma(42) = 12.

MAPLE

with(numtheory): T:=proc(w) local x, y, z; x:=0; y:=w;

for z from 1 to ilog10(w)+1 do x:=10*x+(y mod 10); y:=trunc(y/10); od; x; end:

P:=proc(q) local a, b, k; global n; for n from 1 to q do

if sigma(T(phi(n)))=phi(T(sigma(n))) then print(n); fi; od; end: P(10^12);

MATHEMATICA

Select[Range[400000], DivisorSigma[1, IntegerReverse[EulerPhi[#]]] == EulerPhi[ IntegerReverse[ DivisorSigma[ 1, #]]]&] (* Requires Mathematica version 10 or later *)  (* Harvey P. Dale, Apr 15 2017 *)

CROSSREFS

Cf. A000010, A000203, A069225, A070835, A070856.

Sequence in context: A140184 A264854 A189948 * A025415 A307253 A125849

Adjacent sequences:  A252252 A252253 A252254 * A252256 A252257 A252258

KEYWORD

nonn,base

AUTHOR

Paolo P. Lava, Dec 16 2014

STATUS

approved

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Last modified April 22 06:14 EDT 2019. Contains 322329 sequences. (Running on oeis4.)