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 A251362 #22 Feb 11 2025 23:33:56 %S A251362 25,235741,23517131,274873357929,2357131984859 %N A251362 Numbers n such that n is the concatenation of distinct prime factors of phi(n), in increasing order. %C A251362 Numbers n such that n = A084317(A000010(n)). - _Michel Marcus_, Dec 06 2014 %e A251362 25 is in the sequence since phi(25)=2^2*5, %e A251362 235741 is in the sequence since phi(235741)=2^4*3^2*5*7*41, %e A251362 23517131 is in the sequence since phi(23517131)=2^7*3*5^2*17*131. %t A251362 a251362[n_Integer] := Rest@ Select[Range[n], # == %t A251362 FromDigits[Flatten@IntegerDigits[First@Transpose@FactorInteger[EulerPhi[#]]]] &]; a251362[10^6] (* _Michael De Vlieger_, Dec 03 2014 *) %Y A251362 Cf. A000010, A000040, A084317, A251360, A251361, A251363, A329026. %K A251362 nonn,base,more %O A251362 1,1 %A A251362 _Jahangeer Kholdi_, Dec 03 2014 %E A251362 a(4)-a(5) from _Max Alekseyev_, Feb 11 2025