%I A044631
%S A044631 63,127,191,255,319,383,447,511,575,639,703,767,831,895,959,1023,1087,
%T A044631 1151,1215,1279,1343,1407,1471,1535,1599,1663,1727,1791,1855,1919,1983,
%U A044631 2047,2111,2175,2239,2303,2367,2431,2495,2559
%N A044631 Numbers n such that string 7,7 occurs in the base 8 representation of 
               n but not of n+1.
%C A044631 If A=[A158067] 64*n.^2-2*n (n>0, 62, 252, 570,.,. ,.,); Y=[A010731] 8 
               (8,8,8,.,..,); X=[A044631] 64*n-1 (n>0, 63, 127, 191, ,. .,), we 
               have, for all terms, Pell's equation X^2-A*Y^2=1. Example: 63^2-62*8^2=1; 
               127^2-252*8^2=1; 191^2-570*8^2=1. [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), 
               Mar 12 2009]
%H A044631 Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/
               NonRecursions.html">Non Recursions</a>
%F A044631 a(n)=64*n-1 (n>0) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), 
               Mar 12 2009]
%e A044631 For n=1, a(1)=63; n=2, a(2)=127; n=3, a(3)=191 [From Vincenzo Librandi 
               (vincenzo.librandi(AT)tin.it), Mar 12 2009]
%Y A044631 Cf. A158067, A010731 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), 
               Mar 12 2009]
%Y A044631 Sequence in context: A043450 A031491 A044250 this_sequence A045136 A031895 
               A044314
%Y A044631 Adjacent sequences: A044628 A044629 A044630 this_sequence A044632 A044633 
               A044634
%K A044631 nonn,base
%O A044631 1,1
%A A044631 Clark Kimberling (ck6(AT)evansville.edu)