%I A082718
%S A082718 3,7,13,111,3609,37787
%N A082718 Plateau and depression primes of the form 2*(10^a(n)-1)/9+7*(10^[ a(n)-1 
               ]+1) or (83*10^[ a(n)-1 ]+61)/9.
%C A082718 Prime versus probable prime status and proofs are given in the author's 
               table.
%D A082718 C. Caldwell and H. Dubner, "Journal of Recreational Mathematics", Volume 
               28, No. 1, 1996-97, pp. 1-9.
%H A082718 P. De Geest, <a href="http://www.worldofnumbers.com/deplat.htm">PDP Reference 
               Table</a>
%H A082718 Makoto Kamada, <a href="http://homepage2.nifty.com/m_kamada/math/92229.htm">
               Factorizations of 922...229</a>.
%e A082718 a(n)=13 -> 2*(10^13-1)/9+7*(10^12+1) = 9222222222229.
%Y A082718 Cf. A082697 up to A082720.
%Y A082718 Equals A056265 + 2.
%Y A082718 Sequence in context: A137474 A071087 A038691 this_sequence A154821 A084741 
               A135623
%Y A082718 Adjacent sequences: A082715 A082716 A082717 this_sequence A082719 A082720 
               A082721
%K A082718 nonn,base
%O A082718 0,1
%A A082718 Patrick De Geest (pdg(AT)worldofnumbers.com), Apr 13 2003.
%E A082718 37787 from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008