Search: id:A128269
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%I A128269
%S A128269 1,1,2,2,12,2,60,2,30,2,570,2,4116,2,144,2,39600,2,747694,2,9720308,2,
%T A128269 115638138,2,1261104380,2,3814717230,2,137331022698,2,2137994925180,2,
%U A128269 8901006912,2,274682981784,2,46154014360092,2,29022598622,2
%N A128269 a(1)=1. a(n) = LCM((number of earlier terms which are coprime to n),(sum 
               of the earlier terms which are coprime to n)).
%C A128269 For n > 2, a(n) is even since by induction the sum of coprimes is 1+1+some 
               even numbers. Therefore a(n) = 2 for even n > 2 since only the 1's 
               are coprime.
%H A128269 H. v. Eitzen, <a href="b128269.txt">Table of n, a(n) for n=1..10000</
               a>
%H A128269 Leroy Quet, <a href="http://www.prism-of-spirals.net/">Home Page</a> 
               (listed in lieu of email address)
%e A128269 Among {a(1),a(2),...a(8)} the terms which are coprime to 9 are a(1)=a(2)=1 
               and a(3)=a(4)=a(6)=a(8)=2. There are 6 such terms. And the sum of 
               these terms is 10. So a(8) = LCM(6,10) = 30.
%Y A128269 Cf. A128268.
%Y A128269 Sequence in context: A095215 A076976 A058044 this_sequence A109813 A086595 
               A013605
%Y A128269 Adjacent sequences: A128266 A128267 A128268 this_sequence A128270 A128271 
               A128272
%K A128269 nonn
%O A128269 1,3
%A A128269 Leroy Quet Feb 22 2007
%E A128269 More terms copied from b-file by Hagen von Eitzen (math(AT)von-eitzen.de), 
               Jun 24 2009

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