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%I
%S 3,9,53,375,453,1749,26619
%N Palindromic wing primes (a.k.a. near-repdigit palindromes) of the form (10^a(n)-1)/9+8*10^[ a(n)/2 ].
%C Prime versus probable prime status and proofs are given in the author's table.
%D C. Caldwell and H. Dubner, "Journal of Recreational Mathematics", Volume 28, No. 1, 1996-97, pp. 1-9.
%H Patrick De Geest, World!Of Numbers, <a href="http://www.worldofnumbers.com/wing.htm#pwp191">Palindromic Wing Primes (PWP's)</a>
%H Makoto Kamada, <a href="http://homepage2.nifty.com/m_kamada/math/11911.htm#prime">Prime numbers of the form 11...11911...11</a>
%H <a href="/index/Pri#Pri_rep">Index entries for primes involving repunits</a>.
%F a(n) = 2*A107649(n)+1.
%e a(n)=9 -> (10^9-1)/9+8*10^4 = 111191111.
%Y Cf. A004023, A077775-A077798, A107123-A107127, A107648, A107649, A115073, A183174-A183187.
%K more,nonn,base
%O 1,1
%A _Patrick De Geest_, Nov 16 2002.
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