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A258622
a(1) = 2, a(n+1) = a(n) * (1 + n + a(n))/n.
0
2, 8, 44, 704, 124784, 3114359072, 1616538741858202448, 373313929132642872042128187516973184, 17420411210556488056172048238850552742971470265342499948186222078482064
OFFSET
1,1
COMMENTS
The next term has 139 digits.
LINKS
StackExchange - Mathematics, Quadratic Recurrence Relation (sequence b(n) in the reference).
FORMULA
a(n) ~ n * c^(2^n), where c = 1.36534926036757464312824443040683531215776134381623126072...
MATHEMATICA
FoldList[#1*(1+#2+#1)/#2&, 2, Range@8] (* Ivan N. Ianakiev, Jun 06 2015 *)
PROG
(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
CROSSREFS
Sequence in context: A348107 A139015 A197996 * A290442 A316367 A308599
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Jun 06 2015
STATUS
approved