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%I #11 Sep 08 2022 08:45:17
%S 9,27,41,81,111,113,117,183,191,219,231,261,279,281,309,321,339,363,
%T 377,399,401,411,429,449,461,467,477,479,497,503,513,539,549,567,603,
%U 633,653,659,689,693,707,723,731,737,747,773,843,849,887,891,911,917
%N Numbers n such that the string n10n is the decimal expansion of a prime number.
%e n=9 is in the sequence because n10n = 9109 is prime.
%e n=113 is in the sequence because n10n = 11310113 is prime.
%e n=219 is in the sequence because n10n = 21910219 is prime.
%t n10pQ[n_]:=Module[{idn=IntegerDigits[n]},PrimeQ[FromDigits[Join[idn,{1,0},idn]]]]
%t Select[Range[1000],n10pQ] (* _Harvey P. Dale_, Feb 22 2011 *)
%o (Magma) [ n: n in [0..1000] | IsPrime(Seqint(Intseq(n) cat [0, 1] cat Intseq(n))) ]; // Klaus Brockhaus, Feb 03 2011
%K base,nonn
%O 1,1
%A _Parthasarathy Nambi_, Mar 30 2005