Search: id:A077776
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%I A077776
%S A077776 3,11,27,87,339,363,3159,36155,45305
%N A077776 Palindromic wing primes (a.k.a. near-repdigit palindromes) of the form 
               (10^a(n)-1)-8*10^[ a(n)/2 ].
%C A077776 Prime versus probable prime status and proofs are given in the author's 
               table.
%D A077776 C. Caldwell and H. Dubner, "Journal of Recreational Mathematics", Volume 
               28, No. 1, 1996-97, pp. 1-9.
%H A077776 Patrick De Geest, World!Of Numbers, <a href="http://www.worldofnumbers.com/
               wing.htm#pwp919">Palindromic Wing Primes (PWP's)</a>
%H A077776 Makoto Kamada, <a href="http://homepage2.nifty.com/m_kamada/math/99199.htm">
               Factorizations of 99...99199...99</a>
%e A077776 a(n)=27 -> (10^27-1)-8*10^13 = 999999999999919999999999999.
%t A077776 Do[ If[ PrimeQ[10^n - 8*10^Floor[n/2] - 1], Print[n]], {n, 3, 1000, 2}] 
               (from Robert G. Wilson v (rgwv(at)rgwv.com), Dec 16 2005)
%Y A077776 Cf. A004023, A077775-A077798, A107123-A107127, A107648, A107649, A114633-A114647.
%Y A077776 Sequence in context: A147157 A146826 A059400 this_sequence A113836 A036571 
               A003060
%Y A077776 Adjacent sequences: A077773 A077774 A077775 this_sequence A077777 A077778 
               A077779
%K A077776 nonn,base
%O A077776 1,1
%A A077776 Patrick De Geest (pdg(AT)worldofnumbers.com), Nov 16 2002.

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