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 A227919 #45 May 10 2014 09:52:48 %S A227919 23,29,31,37,53,59,71,73,79,113,131,137,139,173,179,191,193,197,199, %T A227919 233,239,293,311,313,317,373,379,419,431,433,439,479,593,599,613,617, %U A227919 619,673,677,719,733,739,797,839,971,977,1013,1019,1031,1033,1039,1091,1093 %N A227919 Primes which remain prime when rightmost digit is removed. %C A227919 After a(2), all the terms in this sequence have second digit from right 1, 3, 7, or 9. %H A227919 K. D. Bajpai, <a href="/A227919/b227919.txt">Table of n, a(n) for n = 1..10000</a> %e A227919 a(7)= 71 which is prime. Removing the rightmost digit gives 7, which is also prime. %e A227919 a(16)= 191 which is prime. Removing the rightmost digit gives 19, which is also prime. %p A227919 KD:= proc() local a,b; a:= ithprime(n); b:=floor(a/10); if isprime(b) then return (a) :fi; end: seq(KD(),n=1..1000); %o A227919 (PARI) is(n)=isprime(n) && isprime(n\10) \\ _Charles R Greathouse IV_, Oct 12 2013 %Y A227919 Cf. A000040 (prime numbers), A024770 (right-truncatable primes). %Y A227919 Cf. A052025 (palindromic prime is prime right- or left-truncatable). %Y A227919 Cf. A137812 (left- or right-truncatable primes). %K A227919 nonn,base %O A227919 1,1 %A A227919 _K. D. Bajpai_, Oct 10 2013