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A126578
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a(n) = denominator of the sum of reciprocals of the terms in n-th row of triangle A077581.
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1
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1, 3, 4, 105, 4, 85085, 40, 45045, 40040, 66927861, 2520, 167133741775, 27720, 644658718275, 16997552, 4512611027925, 240240, 190103424450275260925, 816816, 3873805630307495883, 28269478608800, 1257729100749186975, 15519504
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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EXAMPLE
| Row 4 of triangle A077581 is (1,3,5,7).
So a(4) is the denominator of 1/1 +1/3 +1/5 + 1/7 = 176/105.
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MATHEMATICA
| row[n_] := Take[Select[Range[n^2], GCD[ #, n] == 1 &], n]; Table[Denominator[Plus @@ (1/# &) /@ row[n]], {n, 23}] (*Chandler*)
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CROSSREFS
| Cf. A077581, A126577.
Sequence in context: A135237 A041253 A156182 * A041351 A066496 A041465
Adjacent sequences: A126575 A126576 A126577 * A126579 A126580 A126581
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KEYWORD
| frac,nonn
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AUTHOR
| Leroy Quet Dec 28 2006
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EXTENSIONS
| Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Dec 29 2006
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