%I
%S 5,71,881,9929,99989,999959,9999971,99999587,999999191,9999999701,
%T 99999999761,999999999959,9999999998489,99999999999971,
%U 999999999997967,9999999999999641,99999999999998807,999999999999998927
%N Lesser of the greatest twin prime pair with n digits.
%C Sum of reciprocals = 0.215331408...
%C Also the numerator of the largest primeoverprime fraction less than 1 that is the ratio of two primes both less than 10^n.  _Cino Hilliard_, Feb 13 2006 [edited by _Jon E. Schoenfield_, Dec 01 2019]
%H Robert G. Wilson v, <a href="/A092250/b092250.txt">Table of n, a(n) for n = 1..1250</a>
%t Array[Block[{k = 10^#  3}, While[! AllTrue[{k, k + 2}, PrimeQ], k = 2]; k] &, 18]
%o (PARI) lasttwpr(n) = { sr=0; for(m=0,n, c=0; forstep(x=10^(m+1)1,10^m,2, if(isprime(x)&& isprime(x2),print1(x2",");sr+=1./(x2);break) ) ); print(); print(sr) }
%K base,nonn
%O 1,1
%A _Cino Hilliard_, Feb 17 2004
