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A258622
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a(1) = 2, a(n+1) = a(n) * (1 + n + a(n))/n.
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0
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2, 8, 44, 704, 124784, 3114359072, 1616538741858202448, 373313929132642872042128187516973184, 17420411210556488056172048238850552742971470265342499948186222078482064
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OFFSET
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1,1
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COMMENTS
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The next term has 139 digits.
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LINKS
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Table of n, a(n) for n=1..9.
StackExchange - Mathematics, Quadratic Recurrence Relation (sequence b(n) in the reference).
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FORMULA
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a(n) ~ n * c^(2^n), where c = 1.36534926036757464312824443040683531215776134381623126072...
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MATHEMATICA
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FoldList[#1*(1+#2+#1)/#2&, 2, Range@8] (* Ivan N. Ianakiev, Jun 06 2015 *)
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PROG
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(Maxima) a(n) := if n = 1 then 2 else a(n-1)*(n+a(n-1))/(n-1) $
makelist(a(n), n, 1, 12); Emanuele Munarini, Mar 23 2017
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CROSSREFS
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Sequence in context: A002833 A139015 A197996 * A290442 A316367 A308599
Adjacent sequences: A258619 A258620 A258621 * A258623 A258624 A258625
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KEYWORD
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nonn
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AUTHOR
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Vaclav Kotesovec, Jun 06 2015
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STATUS
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approved
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