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

237532, 832332, 82953292, 423238803752

Offset

1,1

Comments

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

Links

Table of n, a(n) for n=1..4.

Example

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.

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 *)

Crossrefs

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

Sequence in context: A190933 A122474 A048423 * A251613 A236717 A238928

Adjacent sequences: A251360 A251361 A251362 * A251364 A251365 A251366

Keyword

nonn,base,more,changed

Author

Jahangeer Kholdi, Dec 03 2014

Extensions

a(4) from Max Alekseyev, Feb 10 2025

Status

approved