Search: id:A044712
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%I A044712
%S A044712 80,161,242,323,404,485,566,647,728,809,890,971,1052,1133,1214,1295,
%T A044712 1376,1457,1538,1619,1700,1781,1862,1943,2024,2105,2186,2267,2348,2429,
%U A044712 2510,2591,2672,2753,2834,2915,2996,3077,3158
%N A044712 Numbers n such that string 8,8 occurs in the base 9 representation of 
               n but not of n+1.
%C A044712 If A=[A157507] 81*n.^2-2*n (n>0, 79, 320, 723,.,. ,.,); Y=[A010734] 9 
               (9,9,9,.,..,); X=[A044712] 81*n-1 (n>0, 80, 161, 242, ,. .,), we 
               have, for all terms, Pell's equation X^2-A*Y^2=1. Example: 80^2-79*9^2=1; 
               161^2-320*9^2=1; 242^2-723*9^2=1. [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), 
               Mar 13 2009]
%H A044712 Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/
               NonRecursions.html">Non Recursions</a>
%F A044712 a(n)=81*n-1 (n>0) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), 
               Mar 13 2009]
%e A044712 For n=1, a(1)=80; n=2, a(2)=161; n=3, a(3)=242 [From Vincenzo Librandi 
               (vincenzo.librandi(AT)tin.it), Mar 13 2009]
%Y A044712 Cf. A157597, A010734 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), 
               Mar 13 2009]
%Y A044712 Sequence in context: A043486 A031496 A044331 this_sequence A044412 A044793 
               A157912
%Y A044712 Adjacent sequences: A044709 A044710 A044711 this_sequence A044713 A044714 
               A044715
%K A044712 nonn,base
%O A044712 1,1
%A A044712 Clark Kimberling (ck6(AT)evansville.edu)

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