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%I #15 Jun 24 2017 19:58:25
%S 5,11,9,33,11,21,27,29,71,57,53,39,137,29,53,83,23,33,57,27,113,71,53,
%T 303,321,249,107,261,53,17,81,119,47,513,237,179,123,123,173,27,203,
%U 137,119,77,119,147,83,47,183,161,333,339,611,579
%N 10^n - second largest prime less than 10^n.
%D D. E. Knuth, The Art of Computer Programming, Second Edition, Vol. 2, Seminumerical Algorithms, Chapter 4.5.4 Factoring into Primes, Table 1, Page 390, Addison-Wesley, Reading, MA, 1981.
%H Robert Israel, <a href="/A185201/b185201.txt">Table of n, a(n) for n = 1..1000</a>
%F a(n) = 10^n - precprime(precprime(10^n)-1)
%e a(1)=5 because precprime(10)=7, and precprime(6)=5.
%p seq(10^n - prevprime(prevprime(10^n)),n=1..100); # _Robert Israel_, May 28 2017
%t Table[10^n - NextPrime[10^n, -2], {n,1,50}] (* _G. C. Greubel_, Jun 24 2017 *)
%Y Cf. A033874.
%K nonn
%O 1,1
%A _Washington Bomfim_, Jan 24 2012
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