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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A127680 a(0) = 1. a(n+1) = sum{k=0 to n} a(n-k)*a(floor(k/2)). 1
1, 1, 2, 4, 8, 17, 35, 74, 154, 324, 677, 1422, 2977, 6246, 13086, 27444, 57518, 120600, 252794, 529994, 1111013, 2329187, 4882755, 10236280, 21458943, 44986461, 94308415, 197707134, 414469000, 868886834, 1821517772, 3818600772 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..31.

MATHEMATICA

f[l_List] := Block[{n = Length[l] - 1}, Append[l, Sum[l[[n - k + 1]]*l[[Floor[k/2] + 1]], {k, 0, n}]]]; Nest[f, {1}, 33] (*Chandler*)

CROSSREFS

Cf. A127681.

Sequence in context: A293331 A001357 A058520 * A136750 A274115 A097107

Adjacent sequences:  A127677 A127678 A127679 * A127681 A127682 A127683

KEYWORD

easy,nonn

AUTHOR

Leroy Quet, Jan 23 2007

EXTENSIONS

Extended by Ray Chandler, Feb 13 2007

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 25 10:08 EDT 2019. Contains 321469 sequences. (Running on oeis4.)