login
This site is supported by donations to The OEIS Foundation.

 

Logo

Many excellent designs for a new banner were submitted. We will use the best of them in rotation.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A013589 a(n+1) = a(n)*(a(n)+1)/2. 7
4, 10, 55, 1540, 1186570, 703974775735, 247790242435923759782980, 30700002123226936025189367747945843590228731690, 471245065183069190019624521318729501785547966685566656416776916445985874756815447988119493895 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 0..11

Index entries for sequences of form a(n+1)=a(n)^2 + ...

MAPLE

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

MATHEMATICA

a=4; lst={a}; Do[b=(a+1)*a/2; AppendTo[lst, b]; a=b, {n, 1, 9}]; lst (* Vladimir Joseph Stephan Orlovsky, Mar 16 2010 *)

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

PROG

(Haskell)

a013589 n = a013589_list !! n

a013589_list = iterate a000217 4  -- Reinhard Zumkeller, Apr 10 2014

CROSSREFS

Cf. A000217, A007501, A050542, A050536, A050548, A050909.

Sequence in context: A192444 A197902 A096423 * A225543 A002290 A222569

Adjacent sequences:  A013586 A013587 A013588 * A013590 A013591 A013592

KEYWORD

nonn,changed

AUTHOR

Carl Bellinger (carlb(AT)ctron.com)

EXTENSIONS

One more term from Vladimir Joseph Stephan Orlovsky, Mar 16 2010

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .

Last modified April 24 15:55 EDT 2014. Contains 240988 sequences.