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Search: id:A108176
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| A108176 |
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a(1) = 1, a(n) = (sum{k=1 to floor(n/2)} 1/a(n+1-2k))*(product{k=1 to floor(n/2)} a(n+1-2k)). |
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2
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| 1, 1, 1, 2, 3, 7, 23, 164, 3786, 620973, 2351006074, 1459911295051236, 3432260322166663402961472, 5010795611887306064313121202903094714708, 17198354961167628388233455836547370709483687001035342768448084064
(list; graph; listen)
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OFFSET
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1,4
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FORMULA
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For n>=2, a(n+4) = a(n+1)*(a(n+2) -a(n)a(n+1)) + a(n+2)a(n+3).
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MAPLE
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a[1]:=1: for n from 2 to 25 do a[n]:=sum(1/a[n+1-2*j], j=1..floor(n/2))*product(a[n+1-2*k], k=1..floor(n/2)) od: seq(a[n], n=1..16); (Deutsch)
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MATHEMATICA
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a[1] = 1; a[n_] := a[n] = Sum[1/a[n + 1 - 2k], {k, Floor[n/2]}] Product[ a[n + 1 - 2k], {k, Floor[n/2]}]; Table[ a[n], {n, 15}] (from Robert G. Wilson v (rgwv(AT)rgwv.com), Jun 14 2005)
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CROSSREFS
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Cf. A057438.
Sequence in context: A098544 A090253 A001064 this_sequence A111235 A066356 A006892
Adjacent sequences: A108173 A108174 A108175 this_sequence A108177 A108178 A108179
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), Jun 13 2005
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(AT)rgwv.com) and Emeric Deutsch (deutsch(AT)duke.poly.edu), Jun 14 2005
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