cp's OEIS Frontend

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.

A046884 Doubly automorphic primes: p is k-th prime, ends in k and k is itself prime.

This page as a plain text file.
%I A046884 #14 Mar 23 2022 08:44:46
%S A046884 17,99551,14968819,95517973
%N A046884 Doubly automorphic primes: p is k-th prime, ends in k and k is itself prime.
%H A046884 <a href="/index/Ar#automorphic">Index entries for sequences related to automorphic numbers</a>
%e A046884 p(7)=17 with 7 and 17 both primes. p(9551)=99551 with both 9551 and 99551 primes.
%t A046884 Select[Prime[Prime[Range[6000000]]],PrimePi[#]==Mod[ #,10^IntegerLength[ PrimePi[#]]]&] (* The program takes a long time to run *) (* _Harvey P. Dale_, Jul 05 2012 *)
%t A046884 Prime[Select[Range[5517973],PrimeQ[#]&&StringEndsQ[ToString[Prime[#]],ToString[#]]&]] (* Much faster *) (* _Ivan N. Ianakiev_, Mar 23 2022 *)
%Y A046884 Cf. A046883.
%K A046884 base,hard,nice,nonn
%O A046884 1,1
%A A046884 _Felice Russo_ and _Carlos Rivera_