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%I #8 Aug 02 2015 20:46:25
%S 859,65557,855555559,6555555557,855555555555555559,
%T 85555555555555555559,6555555555555555555557,
%U 85555555555555555555555559,85555555555555555555555555555555555555559,6555555555555555555555555555555555555555555555557
%N Primes such that the outer 2 digits are n and n+1 and all inner digits are 5, where 0 < n < 9.
%F a(x) = 10^(x+1)*n+floor(10^x*5/9)*10+n+1. Output if a(x) is prime.
%t Select[Sort[Flatten[Table[FromDigits[Join[{n},PadRight[{},i,5],{n+1}]],{n,{2,6,8}},{i,50}]]],PrimeQ] (* _Harvey P. Dale_, Aug 02 2015 *)
%o (PARI) n10np1(n) = { local(x,y,k); for(x=1,n, for(k=1,8, y=10^(x+1)*k+floor(10^x*5/9)*10+k+1; if(isprime(y),print1(y",")) ) ) }
%K easy,nonn,base
%O 1,1
%A _Cino Hilliard_, Jul 11 2005
%E One more term (a(10)) from _Harvey P. Dale_, Aug 02 2015
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