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 A227919 Primes which remain prime when rightmost digit is removed. 8
 23, 29, 31, 37, 53, 59, 71, 73, 79, 113, 131, 137, 139, 173, 179, 191, 193, 197, 199, 233, 239, 293, 311, 313, 317, 373, 379, 419, 431, 433, 439, 479, 593, 599, 613, 617, 619, 673, 677, 719, 733, 739, 797, 839, 971, 977, 1013, 1019, 1031, 1033, 1039, 1091, 1093 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS After a(2), all the terms in this sequence have second digit from right 1, 3, 7, or 9. LINKS K. D. Bajpai, Table of n, a(n) for n = 1..10000 EXAMPLE a(7)= 71 which is prime. Removing the rightmost digit gives 7, which is also prime. a(16)= 191 which is prime. Removing the rightmost digit gives 19, which is also prime. MAPLE 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); PROG (PARI) is(n)=isprime(n) && isprime(n\10) \\ Charles R Greathouse IV, Oct 12 2013 CROSSREFS Cf. A000040 (prime numbers), A024770 (right-truncatable primes). Cf. A052025 (palindromic prime is prime right- or left-truncatable). Cf. A137812 (left- or right-truncatable primes). Sequence in context: A112681 A078500 A155913 * A240898 A244077 A277206 Adjacent sequences:  A227916 A227917 A227918 * A227920 A227921 A227922 KEYWORD nonn,base AUTHOR K. D. Bajpai, Oct 10 2013 STATUS approved

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Last modified October 23 23:51 EDT 2019. Contains 328379 sequences. (Running on oeis4.)