A069809 Numbers k such that gcd(k, phi(k)) = tau(k).
1, 8, 9, 18, 24, 40, 56, 84, 88, 104, 136, 152, 156, 184, 228, 232, 248, 296, 328, 344, 360, 372, 376, 424, 444, 472, 488, 516, 536, 568, 584, 632, 664, 712, 732, 776, 792, 804, 808, 824, 856, 872, 876, 904, 948, 1016, 1048, 1096, 1112, 1164, 1192, 1208
Offset: 1
Links
- Georg Fischer, Table of n, a(n) for n = 1..2000 (first 1835 terms by Marius A. Burtea)
Programs
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Magma
[n: n in [1..2000] | GCD(n,EulerPhi(n)) eq NumberOfDivisors(n) ];// Marius A. Burtea, Dec 28 2018
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Mathematica
Select[Range[1300], GCD[#, EulerPhi[#]] == DivisorSigma[0, #] &] (* Jayanta Basu, Mar 21 2013 *)
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PARI
for(n=1,1592,if(gcd(n,eulerphi(n))==numdiv(n),print1(n,",")))