login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A211291 a(n) = number of n-lettered words in the alphabet {1, 2, 3} with as many occurrences of the substring (consecutive subword) [1, 1, 2] as of [1, 3, 1]. 0
1, 3, 9, 25, 69, 192, 537, 1508, 4249, 12009, 34044, 96795, 275989, 789040, 2261594, 6497986, 18712521, 54002913, 156162531, 452435327, 1313117536, 3817402150, 11114803333, 32408592752, 94623871921, 276620070867, 809602760028, 2372089156969, 6957106088502, 20423727601032, 60009849519354 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..30.

Shalosh B. Ekhad and Doron Zeilberger, Automatic Solution of Richard Stanley's Amer. Math. Monthly Problem #11610 and ANY Problem of That Type, arXiv preprint arXiv:1112.6207, 2011. See subpages for rigorous derivations of g.f., recurrence, asymptotics for this sequence.

CROSSREFS

Sequence in context: A098182 A211300 A211293 * A211294 A211297 A297590

Adjacent sequences:  A211288 A211289 A211290 * A211292 A211293 A211294

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Apr 07 2012

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 January 19 22:12 EST 2022. Contains 350466 sequences. (Running on oeis4.)