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 A115894 #9 Jul 15 2021 21:23:39
%S A115894 1,2,5,16,534,7412,17280,146533,633932,1424705,5879645
%N A115894 Numbers k such that phi(k)*prime(k) is a palindrome.
%e A115894 phi(17280)*prime(17280) = 4608*191461 = 882252288.
%t A115894 pppQ[n_]:=Module[{c=IntegerDigits[EulerPhi[n]Prime[n]]},c == Reverse[c]]; Select[Range[6000000],pppQ] (* _Harvey P. Dale_, Aug 01 2012 *)
%Y A115894 Cf. A084122, A115891, A115893.
%K A115894 nonn,base
%O A115894 1,2
%A A115894 _Giovanni Resta_, Feb 06 2006