This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A251363 #24 Feb 22 2025 01:25:13 %S A251363 237532,832332,82953292,423238803752 %N A251363 Numbers n such that n is the concatenation of distinct prime factors of phi(n), in decreasing order. %C A251363 Numbers n such that n = A085307(A000010(n)). - _Michel Marcus_, Dec 06 2014 %e A251363 237532 is in the sequence since phi(237532)=23*7*5*3^2*2^4, %e A251363 832332 is in the sequence since phi(832332)=83*23*3^2*2^4, and %e A251363 82953292 is in the sequence since phi(82953292)=829*53*29*2^5. %t A251363 a251363[n_Integer] := %t A251363 Rest@ Select[Range[n], # == FromDigits[Flatten@ IntegerDigits[ %t A251363 Sort[First@ Transpose@ FactorInteger[EulerPhi[#]], Greater]]] &]; a251363[10^6] (* _Michael De Vlieger_, Dec 03 2014 *) %Y A251363 Cf. A000010, A000040, A085307, A251360, A251361, A251362. %K A251363 nonn,base,more %O A251363 1,1 %A A251363 _Jahangeer Kholdi_, Dec 03 2014 %E A251363 a(4) from _Max Alekseyev_, Feb 10 2025