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 A110268 Consider the sequence A110566: lcm{1,2,...,n}/denominator of harmonic number H(n). a(n) is the factor that is changed going from A110566(n) to A110566(n+1). 1
 1, 1, 1, 1, 3, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 5, 3, 1, 1, 3, 5, 1, 3, 1, 1, 1, 1, 1, 11, 1, 1, 1, 1, 1, 1, 1, 1, 7, 1, 11, 1, 1, 1, 1, 7, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 3, 1, 1, 3, 1, 1, 3, 1, 1, 1, 1, 11, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 11, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 25, 1, 1, 1, 1, 5 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,5 COMMENTS a(n) is always an odd prime power, A061345. LINKS EXAMPLE A110566(4) through A110566(10) are {1,1,3,3,3,1,1}, therefore the factors are 1,3,1,1,3,1. MATHEMATICA f[n_] := LCM @@ Range[n]/Denominator[HarmonicNumber[n]]; Table[ LCM[f[n], f[n + 1]]/GCD[f[n], f[n + 1]], {n, 104}] PROG (PARI) f(n) = lcm(vector(n, k, k))/denominator(sum(k=1, n, 1/k)); a(n) = my(x = f(n+1)/f(n)); if (x > 1, x, 1/x); \\ Michel Marcus, Mar 07 2018 CROSSREFS Cf. A110566, A112811. Sequence in context: A267863 A262681 A076498 * A058965 A226306 A124921 Adjacent sequences:  A110265 A110266 A110267 * A110269 A110270 A110271 KEYWORD nonn AUTHOR Robert G. Wilson v, Sep 17 2005 STATUS approved

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Last modified August 16 07:50 EDT 2022. Contains 356160 sequences. (Running on oeis4.)