Search: id:A136183
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%I A136183
%S A136183 0,2,3,6,5,14,7,14,12,22,11,44,13,30,33,30,17,50,19,56,45,46,23,104,30,
%T A136183 54,39,76,29,143,31,62,69,70,75,158,37,78,81,166,41,154,43,116,153,94,
%U A136183 47,224,56,122,105,136,53,158,115,230,117,118,59,400,61,126,213,126,135
%N A136183 a(n) = Sum_{k=1 to d(n)-1} LCM(b(k),b(k+1)), where b(k) is the kth positive 
               divisor of n and d(n) = number of positive divisors of n.
%C A136183 a(n) = sum of the terms in row n of A136181.
%H A136183 H. v. EItzen, <a href="b136183.txt">Table of n, a(n) for n=1..10000</
               a>
%H A136183 Leroy Quet, <a href="http://www.prism-of-spirals.net/">Home Page</a> 
               (listed in lieu of email address)
%e A136183 The positive divisors of 20 are 1,2,4,5,10,20. LCM(1,2)=2. LCM(2,4)=4. 
               LCM(4,5)=20. LCM(5,10)=10. And LCM(10,20)=20. So a(20) = 2+4+20+10+20 
               = 56.
%p A136183 A136181row := proc(n) local dvs; dvs := sort(convert(numtheory[divisors](n),
               list)) ; seq(lcm(op(d-1,dvs),op(d,dvs)),d=2..nops(dvs)) ; end: A136183 
               := proc(n) if n = 1 then 0; else add(l,l= A136181row(n) ) ; fi; end: 
               seq(A136183 (n),n=1..70) ; [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), 
               Jul 20 2009]
%o A136183 (PARI) A136183(n) = local(d=divisors(n)); vector(#d-1,x,lcm(d[x],d[x+1]))*vector(#d-1,
               x,1)~
%Y A136183 Cf. A136180, A136181, A136182.
%Y A136183 Sequence in context: A002517 A053570 A129647 this_sequence A100211 A071257 
               A067392
%Y A136183 Adjacent sequences: A136180 A136181 A136182 this_sequence A136184 A136185 
               A136186
%K A136183 nonn
%O A136183 1,2
%A A136183 Leroy Quet Dec 19 2007
%E A136183 Extended beyond a(12) by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), 
               Jul 20 2009

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