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A081530
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a(n) = running sum of the first n harmonic numbers, multiplied by the LCM of 1..n.
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3
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1, 5, 26, 77, 522, 669, 5772, 13827, 48610, 55991, 699612, 785633, 11359222, 12530955, 13726712, 29889983, 550271934, 593094837, 12094689300, 12932216325, 13780828710, 14640022575, 356714770680, 376932115005, 1986818142426
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OFFSET
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1,2
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COMMENTS
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Consider triangle in A081525. Write terms in k-th row with denominator = LCM of terms in that row. Sequence gives sum of numerators of terms in n-th row.
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LINKS
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FORMULA
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a(n) = lcm(1..n)*(n+1)*(H(n+1)-1), where H(n) is the n-th harmonic number. - C. Ronaldo (aga_new_ac(AT)hotmail.com), Dec 19 2004
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EXAMPLE
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(1), 2*(1 + 3/2), 6*(1 + 3/2 + 11/6), 12*(1 + 3/2 + 11/6 + 25/12).
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MAPLE
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H:=n->add(1/i, i=1..n):seq((n+1)*ilcm(seq(j, j=1..n))*(H(n+1)-1), n=1..30); # C. Ronaldo
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MATHEMATICA
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Table[Sum[HarmonicNumber[k], {k, n}] LCM @@ Range[n], {n, 36}] (* Wouter Meeussen *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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