login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)

A268939 as a simple table

n a(n)
1 4
2 16
3 60
4 220
5 788
6 2780
7 9684
8 33404
9 114292
10 388444
11 1312788
12 4415548
13 14790836
14 49369628
15 164279892
16 545170172
17 1804855540
18 5962578652
19 19661140116
20 64722276796
21 212738159924
22 698312564636
23 2289419181780
24 7497612860540

[4,16,60,220,788,2780,9684,33404,114292,388444,
 1312788,4415548,14790836,49369628,164279892,
 545170172,1804855540,5962578652,19661140116,
 64722276796,212738159924,698312564636,
 2289419181780,7497612860540]

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 December 1 16:44 EST 2021. Contains 349430 sequences. (Running on oeis4.)