Search: id:A146569
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%I A146569
%S A146569 102564,128205,153846,179487,205128,230769,102564102564,128205128205,
%T A146569 153846153846,179487179487,205128205128,230769230769,102564102564102564,
%U A146569 128205128205128205,153846153846153846,179487179487179487
%N A146569 Numbers m with the property that shifting the rightmost digit of m to 
               the left end multiplies the number by 4.
%C A146569 a(13) <= 102564102564102564. [From Donovan Johnson (donovan.johnson(AT)yahoo.com), 
               Jun 06 2009]
%C A146569 The condition is equivalent to the numbers being of the form 10*m+d with 
               a k-digit number m and a non-zero digit d such that 4*(10*m+d) = 
               10^k * d + m, i.e. 39*m = (10^k - 4)*d. Checking modulo 13, this 
               implies k = 5 (mod 6). Also, m >= 10^(k-1) implies d >= 4. Each such 
               k and d leads to a solution. [From Hagen von Eitzen (math(AT)von-eitzen.de), 
               Jun 26 2009]
%F A146569 If n = 6*k + r with 1 <= r <=6, then a(n) = (10^(6*k)-1)/(10^6-1) * a(r) 
               as well as a(n) = floor( (r+3)/39 * 10^(6*(k+1)) ) [From Hagen von 
               Eitzen (math(AT)von-eitzen.de), Jun 26 2009]
%o A146569 (PARI) a(n) = local(r=(n-1)%6+1,k=(n-r)/6);floor((r+3)/39*10^(6*(k+1))) 
               [From Hagen von Eitzen (math(AT)von-eitzen.de), Jun 26 2009]
%Y A146569 Cf. A146088.
%Y A146569 Sequence in context: A074669 A010329 A034089 this_sequence A081463 A014884 
               A015330
%Y A146569 Adjacent sequences: A146566 A146567 A146568 this_sequence A146570 A146571 
               A146572
%K A146569 nonn,base
%O A146569 1,1
%A A146569 N. J. A. Sloane, based on correspondence from William A. Hoffman III 
               (whoff(AT)robill.com), Apr 10 2009
%E A146569 a(7)-a(12) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Jun 06 
               2009
%E A146569 More terms from Hagen von Eitzen (math(AT)von-eitzen.de), Jun 26 2009

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