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Search: id:A123702
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| A123702 |
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a(1)=a(2)=1. For n >= 3, a(n) = (product{k=1 to n-1} a(k)) - (sum{j=1 to n-1} a(j)). |
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+0
2
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| 1, 1, -1, -2, 3, 4, 18, 408, 175824, 30989858688, 960376803619751958528, 922323604960653729254933704147036248735744, 850680832267616036448642743307003648114050501920269009809993262836200003241653567488
(list; graph; listen)
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OFFSET
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1,4
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COMMENT
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a(3) and a(4) are the only negative terms of the sequence.
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FORMULA
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For n >= 5, a(n) = a(n-1) a(n-2) (a(n-1)-1) /(a(n-2)-1).
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MATHEMATICA
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f[l_List] := Append[l, Times @@ l - Plus @@ l]; Nest[f, {1, 1}, 11] (*Chandler*)
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CROSSREFS
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Cf. A123703.
Sequence in context: A037394 A037430 A077407 this_sequence A067805 A092837 A058772
Adjacent sequences: A123699 A123700 A123701 this_sequence A123703 A123704 A123705
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KEYWORD
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easy,sign
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AUTHOR
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Leroy Quet (q1qq2qqq3qqqq(AT)yahoo.com), Oct 08 2006
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EXTENSIONS
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Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Oct 09 2006
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