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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A228515 Nonlinear recursion: a(n)=a(n-1) + product(a(n-2i+1)-a(n-2i), i=1..(n-1)/2). 0
1, 2, 4, 6, 8, 12, 20, 52, 308, 8500, 2105652, 17181974836, 36028814200938804, 618970019678718951650500916, 22300745198530623760505737951367313156481332 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Initial conditions: a(1)=1; a(2)=1; a(3)=4;

With a(3)=3, the recursion gives the positive integers.

LINKS

Table of n, a(n) for n=1..15.

MATHEMATICA

a[1]:= 1; a[2]:= 2; a[3]:= 4;

a[n_Integer]:=a[n]=a[n-1]+ Times@@Table[(a[n-2i+1]-a[n-2i]), {i, 1, (n-1)/2}];

Table[a[n], {n, 1, 15}]

CROSSREFS

Sequence in context: A292994 A323114 A118563 * A164145 A140999 A168267

Adjacent sequences:  A228512 A228513 A228514 * A228516 A228517 A228518

KEYWORD

nonn,easy

AUTHOR

Olivier Gérard, Aug 24 2013

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 November 18 19:59 EST 2019. Contains 329288 sequences. (Running on oeis4.)