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%I A025550 #68 Feb 16 2025 08:32:35
%S A025550 1,4,23,176,563,6508,88069,91072,1593269,31037876,31730711,744355888,
%T A025550 3788707301,11552032628,340028535787,10686452707072,10823198495797,
%U A025550 10952130239452,409741429887649,414022624965424,17141894231615609,743947082888833412,750488463554668427
%N A025550 a(n) = ( 1/1 + 1/3 + 1/5 + ... + 1/(2*n-1) )*LCM(1, 3, 5, ..., 2*n-1).
%C A025550 Or, numerator of 1/1 + 1/3 + ... + 1/(2n-1) up to a(38).
%C A025550 Following similar remark by _T. D. Noe_ in A025547, this coincides with f(n) = numerator of 1 + 1/3 + 1/5 + 1/7 + ... + 1/(2n-1) iff n <= 38. But a(39) = 18048708369314455836683437302413, f(39) = 1640791669937677803334857936583. Note that f(n) = numerator(digamma(n+1/2)/2 + log(2) + euler_gamma/2). - _Paul Barry_, Aug 19 2005 [See A350669(n-1).]
%H A025550 Georg Fischer, <a href="/A025550/b025550.txt">Table of n, a(n) for n = 1..200</a> (first 39 terms from Jean-François Alcover)
%H A025550 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/JeepProblem.html">Jeep Problem</a>
%p A025550 a:= n-> (f-> add(1/p, p=f)*ilcm(f[]))([2*i-1$i=1..n]):
%p A025550 seq(a(n), n=1..40);  # _Alois P. Heinz_, Apr 16 2015
%t A025550 Table[(Total[1/Range[1,2n-1,2]])LCM@@Range[1,2n-1,2],{n,30}] (* _Harvey P. Dale_, Sep 09 2020 *)
%o A025550 (Haskell)
%o A025550 a025550 n = numerator $ sum  $ map (1 %) $ take n [1, 3 ..]
%o A025550 -- _Reinhard Zumkeller_, Jan 22 2012
%o A025550 (PARI) a(n)=my(v=vector(n,i,2*i-1));sum(i=1,#v,1/v[i])*lcm(v) \\ _Charles R Greathouse IV_, Feb 28 2013
%o A025550 (Magma) [&+[1/d: d in i]*Lcm(i) where i is [1..2*n-1 by 2]: n in [1..21]]; // _Bruno Berselli_, Apr 16 2015
%Y A025550 Cf. A025547, A075135, A002428, A350669.
%K A025550 nonn,easy,nice,frac
%O A025550 1,2
%A A025550 _Clark Kimberling_
%E A025550 Value of a(39) corrected by _Jean-François Alcover_, Apr 16 2015

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