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A127679
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a(n) = denominator of b(n), where b(1) = 1, b(n+1) = (sum{k=1 to n} b(k))/product{j=1 to n} b(j).
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1
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1, 1, 1, 1, 2, 4, 6, 15, 35, 119, 221, 1703, 31571, 444163, 62571693, 16130221953, 31653658032799, 1139752929797333269, 190765682365696256860989, 13391304481955883169111997465697
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,5
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FORMULA
| For n >= 4, b(n) = 1 +(b(n-1)-1)/b(n-2).
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MATHEMATICA
| f[l_List] := Append[l, Plus @@ l/Times @@ l]; Denominator[Nest[f, {1}, 20]] (*Chandler*)
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CROSSREFS
| Cf. A127678.
Sequence in context: A077639 A039791 A192536 * A049022 A136033 A099315
Adjacent sequences: A127676 A127677 A127678 * A127680 A127681 A127682
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KEYWORD
| easy,frac,nonn
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AUTHOR
| Leroy Quet Jan 23 2007
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EXTENSIONS
| Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Feb 13 2007
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