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A247115
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Denominator of the harmonic mean of the first n heptagonal numbers.
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2
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1, 4, 151, 1315, 73396, 667109, 10749479, 399851303, 401511863, 18933826729, 246810236317, 4700047812703, 145981746528913, 9796912235587651, 9810925971351679, 9823210739716249, 403196782523223569, 11704197956499986461, 269433333504358946963
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OFFSET
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1,2
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LINKS
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EXAMPLE
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a(3) = 151 because the first 3 heptagonal numbers are [1,7,18], and 3/(1/1+1/7+1/18) = 378/151.
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PROG
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(PARI)
harmonicmean(v) = #v / sum(k=1, #v, 1/v[k])
s=vector(30); for(n=1, #s, s[n]=denominator(harmonicmean(vector(n, k, k*(5*k-3)/2)))); s
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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