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