A013589 - OEIS (original) (raw)

A013589

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

8

4, 10, 55, 1540, 1186570, 703974775735, 247790242435923759782980, 30700002123226936025189367747945843590228731690, 471245065183069190019624521318729501785547966685566656416776916445985874756815447988119493895

FORMULA

a(n) ~ 2 * c^(2^n), where c = 2.29524458756644851072790131811443639562180382439442714497... . - Vaclav Kotesovec, Dec 17 2014

MAPLE

f := proc(n) options remember; if n = 0 then 4 else 1/2*f(n-1)*(f(n-1)+1) fi end

MATHEMATICA

NestList[# (#+1)/2&, 4, 10] (* Harvey P. Dale, Sep 20 2012 *)

PROG

(Haskell)

a013589 n = a013589_list !! n

AUTHOR

Carl Bellinger (carlb(AT)ctron.com)