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 A069866 #16 Dec 07 2018 17:18:47
%S A069866 2,3,5,7,13,17,23,37,43,47,53,67,73,83,97,131,137,173,179,223,229,271,
%T A069866 331,337,353,359,373,379,431,479,523,571,631,653,659,673,773,823,829,
%U A069866 853,859,929,937,953,971,1031,1373,1433,1439,1733,2029,2053,2131,2137
%N A069866 Primes in which repeatedly deleting the most significant digit then the least significant digit gives a prime at every step until a single-digit prime remains.
%H A069866 Michael De Vlieger, <a href="/A069866/b069866.txt">Table of n, a(n) for n = 1..645</a> (Primes p <= 10^7).
%t A069866 Select[Prime@ Range@ 400, AllTrue[FromDigits /@ Rest@ Fold[Append[#1, Delete[Last[#1], 1 - 2 Boole[EvenQ@ #2]]] &, {#}, Range[Length@ # - 1]] &@ IntegerDigits[#], PrimeQ] &] (* _Michael De Vlieger_, Jan 20 2018 *)
%Y A069866 Cf. A024770, A033664, A069867.
%K A069866 base,nonn
%O A069866 1,1
%A A069866 _Amarnath Murthy_, Apr 21 2002
%E A069866 Corrected and extended by Larry Reeves (larryr(AT)acm.org), Sep 24 2002