A263241 - OEIS

%I #21 Oct 16 2021 22:31:33

%S 13,17,37,79,107,113,149,157,167,179,199,337,347,359,389,709,739,769,

%T 1009,1223,1229,1559,1669,3889,7229,10007,10009,10909,11717,11719,

%U 12227,12323,12829,13337,13933,14143,14447,14449,14549,14843,14947,15053,16063,16267,16567,16763

%N Lesser of emirp pairs that are merely reversals of their end digits.

%C The first digit is always smaller than last digit.

%t Select[Range[20000], And @@ PrimeQ[{#, IntegerReverse[#]}] && ! PalindromeQ[#] && First[(d = IntegerDigits[#])] < Last[d] && PalindromeQ[Most@ Rest@ IntegerDigits[#]] &] (* _Amiram Eldar_, Oct 16 2021 *)

%o (PARI) isok(p) = my(dp=digits(p), dr=Vecrev(dp), r=fromdigits(dr)); if (isprime(r) && (r>p) && isprime(p), sum(i=2, #dp-1, dp[i]==dr[i]) == #dp-2); \\ _Michel Marcus_, Oct 16 2021

%Y Cf. A006567, A109308, A263240, A263242.

%K nonn,base

%O 1,1

%A _Lekraj Beedassy_, Oct 13 2015

%E Missing 179 added by _Zak Seidov_, Oct 15 2021