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 A227916 #23 May 10 2014 09:55:16 %S A227916 13,17,23,37,43,47,53,67,73,83,97,103,107,113,131,137,167,173,179,197, %T A227916 211,223,229,241,271,283,307,311,313,317,331,337,347,353,359,367,373, %U A227916 379,383,389,397,419,431,443,461,467,479,503,523,541,547,571,607,613,617 %N A227916 Primes that remain prime when the leftmost digit is removed. %H A227916 K. D. Bajpai, <a href="/A227916/b227916.txt">Table of n, a(n) for n = 1..10000</a> %e A227916 a(11)= 97 which is prime. Removing the leftmost digit gives 7, also prime. %e A227916 a(28)= 311 which is prime. Removing the leftmost digit gives 11, also prime. %p A227916 KD:= proc() local a,b,c,d; a:=ithprime(n);b:=length(a); c:=floor(a/(10^(b-1)));d:=a-c*(10^(b-1));if isprime(d) then return(a):fi; end:seq(KD(),n=1..5000); %Y A227916 Cf. A000040 (prime numbers), A024785 (left-truncatable primes). %Y A227916 Cf. A137812 (left- or right-truncatable primes). %Y A227916 Cf. A227919 (primes which remain prime when rightmost digit is removed). %K A227916 nonn,base %O A227916 1,1 %A A227916 _K. D. Bajpai_, Oct 13 2013