A258622 a(1) = 2, a(n+1) = a(n) * (1 + n + a(n))/n.

2, 8, 44, 704, 124784, 3114359072, 1616538741858202448, 373313929132642872042128187516973184, 17420411210556488056172048238850552742971470265342499948186222078482064

Offset

1,1

Comments

The next term has 139 digits.

Links

Table of n, a(n) for n=1..9.

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

Adjacent sequences: A258619 A258620 A258621 * A258623 A258624 A258625

Keyword

nonn

Author

Vaclav Kotesovec, Jun 06 2015

Status

approved