A039779 Numbers k such that phi(k) is equal to A008473(k).
1, 54, 99, 112, 540, 3344, 4743, 6720, 7644, 8307, 11088, 12852, 15225, 20300, 22320, 83160, 86304, 94944, 129504, 160208, 186992, 200640, 205712, 207264, 266266, 280592, 331731, 364941, 383724, 404550, 441232, 445050, 447876, 449072, 454575, 458052, 497781
Offset: 1
Keywords
Examples
phi(54) = 18, 54 = 2^1*3^3, (2+1)*(3+3) = 18.
Links
- Amiram Eldar, Table of n, a(n) for n = 1..866 (terms below 10^10)
Programs
-
Mathematica
Reap[For[n = 1, n < 500000, n++, If[EulerPhi[n] == Times @@ Plus @@@ FactorInteger[n], Print[n]; Sow[n]]]][[2, 1]] (* Jean-François Alcover, May 06 2017 *)
-
PARI
is(k) = {my(f = factor(k)); eulerphi(f) == prod(i = 1, #f~, f[i, 1] + f[i, 2]);} \\ Amiram Eldar, Dec 04 2024