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a(n) = denominator of Sum_{i=1..n} 1/A171397(i).
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%I #19 Aug 30 2024 21:20:29

%S 1,2,6,12,60,20,140,280,2520,27720,27720,360360,360360,360360,720720,

%T 12252240,4084080,77597520,77597520,77597520,1784742960,1784742960,

%U 8923714800,8923714800,80313433200,11473347600,332727080400,332727080400,10314539492400,937685408400,937685408400

%N a(n) = denominator of Sum_{i=1..n} 1/A171397(i).

%H Alois P. Heinz, <a href="/A375524/b375524.txt">Table of n, a(n) for n = 1..2082</a>

%e The first few sums are 1, 3/2, 11/6, 25/12, 137/60, 49/20, 363/140, 761/280, 7129/2520, 80939/27720, 83249/27720, 1109957/360360, 1135697/360360, 1159721/360360, 2364487/720720, ...

%p b:= n-> (l-> add(l[i]*11^(i-1), i=1..nops(l)))(convert(n,base,10)):

%p g:= proc(n) option remember; `if`(n<1, 0, g(n-1)+1/b(n)) end:

%p a:= n-> denom(g(n)):

%p seq(a(n), n=1..31); # _Alois P. Heinz_, Aug 30 2024

%Y Cf. A171397, A375805, A375523, A001008/A002805.

%K nonn,frac

%O 1,2

%A _N. J. A. Sloane_, Aug 30 2024.