%I A108821
%S A108821 647,24443,84449,644447,24444443,64444444447,2444444444443,
%T A108821 84444444444449,2444444444444444444444444444443,
%U A108821 84444444444444444444444444444444444449
%N A108821 Primes such that the outer 2 digits are n and n+1 and all inner digits 
               are 4, where 0 < n < 9.
%F A108821 a(x) = 10^(x+1)*n+floor(10^x*4/9)*10+n+1. Output if a(x) is prime.
%o A108821 (PARI) n10np1(n) = { local(x,y,k); for(x=1,n, for(k=1,8, y=10^(x+1)*k+floor(10^x*4/
               9)*10+k+1; if(isprime(y),print1(y",")) ) ) }
%Y A108821 Sequence in context: A067845 A057942 A046020 this_sequence A035885 A114827 
               A034281
%Y A108821 Adjacent sequences: A108818 A108819 A108820 this_sequence A108822 A108823 
               A108824
%K A108821 easy,nonn,base
%O A108821 1,1
%A A108821 Cino Hilliard (hillcino368(AT)gmail.com), Jul 11 2005