A251363 Numbers n such that n is the concatenation of distinct prime factors of phi(n), in decreasing order.

237532, 832332, 82953292, 423238803752

Offset: 1

Author

Jahangeer Kholdi, Dec 03 2014

Keywords

• nonn
• base
• more

Comments

Numbers n such that n = A085307(A000010(n)). - Michel Marcus, Dec 06 2014

Examples

			237532 is in the sequence since phi(237532)=23*7*5*3^2*2^4,
832332 is in the sequence since phi(832332)=83*23*3^2*2^4, and
82953292 is in the sequence since phi(82953292)=829*53*29*2^5.
		

Crossrefs

Cf. A000010, A000040, A085307, A251360, A251361, A251362.

Programs

Mathematica

a251363[n_Integer] :=
Rest@ Select[Range[n], # == FromDigits[Flatten@ IntegerDigits[
Sort[First@ Transpose@ FactorInteger[EulerPhi[#]], Greater]]] &]; a251363[10^6] (* Michael De Vlieger, Dec 03 2014 *)

Extensions

a(4) from Max Alekseyev, Feb 10 2025