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%I #4 Oct 01 2013 17:58:13
%S 293,6997,8999,69997,299993,6999997,89999999,29999999993,69999999997,
%T 89999999999999999999,699999999999999999997,
%U 299999999999999999999999999993,899999999999999999999999999999
%N Primes such that the outer 2 digits are n and n+1 and all inner digits are 9, where 0 < n < 9.
%F a(x) = 10^(x+1)*n+(10^x-1)*10+n+1. Output if a(x) is prime.
%o (PARI) n10np9(n,d) = { local(x,y,k); for(x=1,n, for(k=1,8, y=10^(x+1)*k+(10^x-1)*10+k+1; if(isprime(y),print1(y",")) ) ) }
%K easy,nonn,base
%O 1,1
%A _Cino Hilliard_, Jul 11 2005
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