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 A091294 Numbers n such that phi(n) = phi(3n+1). 1
 75973, 301513, 2053393, 3404053, 4022573, 5399123, 6461473, 8395613, 9848813, 11804173, 14124133, 15680573, 17173333, 20705533, 23609083, 28988353, 30290563, 32845633, 35025943, 36791813, 39630803, 42598663, 43605943, 44116333, 53795083, 54396533, 54563693 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Is it accidental that most terms have form 10k+3? LINKS Donovan Johnson, Table of n, a(n) for n = 1..100 MATHEMATICA Do[If[Equal[EulerPhi[n], EulerPhi[3*n+1]], Print[n]], {n, 1, 100000000}] PROG (PARI) is(n)=my(t=eulerphi(3*n+1)); t

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Last modified June 15 15:25 EDT 2024. Contains 373407 sequences. (Running on oeis4.)