A237798 Numbers k such that phi(k) equals the product of two numbers: sums of prime factors of k, with and without repetition.

750, 5022, 8037, 18250, 60249, 105669, 1760490, 1965270, 4626489, 62546070, 202631245, 441416073, 286952692809

Offset: 1

Author

Giovanni Resta, Feb 13 2014

Keywords

• nonn

Comments

25446095286407049 and 27093686218810118911929 are terms.

Examples

			750 = 2*3*5^3 is a term since phi(750) = 200 = (2+3+5) * (2+3+5+5+5).
		

Crossrefs

Cf. A000010, A001414, A008472, A073396.

Programs

Mathematica

Select[Range[2, 10^5], (f=FactorInteger@#; EulerPhi[#] == Total[First /@ f]* Total[Times @@@ f]) &]