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Search: id:A115587
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| A115587 |
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a(n) = denominator of b(n), where b(1) = 1, b(n+1) = sum{k=1 to n} b(k)^((-1)^(n-k)). |
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4
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| 1, 1, 1, 1, 2, 4, 52, 559, 2023580, 639046564, 73885083538076135, 13974134129149036419614094980, 9508386737708519692119190558953351866716894940, 167312950453078829361896561420857502596441619698513063185995475418519527687170
(list; graph; listen)
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OFFSET
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1,5
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EXAMPLE
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{b(n)} begins 1, 1, 2, 4, 13/2, 43/4,...
So b(7) = 1 + 1 + 1/2 + 4 + 2/13 + 43/4 = 905/52, and therefore a(7) = 52.
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MAPLE
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b[1]:=1: for n from 1 to 14 do b[n+1]:=sum(b[k]^((-1)^(n-k)), k=1..n): a[n]:=denom(b[n]) od: seq(a[n], n=1..14); - Emeric Deutsch (deutsch(AT)duke.poly.edu), Mar 30 2006
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CROSSREFS
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Cf. A115600, A115601, A115602.
Sequence in context: A032019 A085325 A082661 this_sequence A018337 A092389 A005274
Adjacent sequences: A115584 A115585 A115586 this_sequence A115588 A115589 A115590
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KEYWORD
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frac,nonn
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), Mar 13 2006
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EXTENSIONS
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More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Mar 30 2006
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