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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A211287 a(n) = number of n-lettered words in the alphabet {1, 2, 3} with as many occurrences of the substring (consecutive subword) [1, 1, 1] as of [2, 2, 2]. 1
1, 3, 9, 25, 71, 201, 571, 1621, 4611, 13127, 37415, 106763, 304991, 872267, 2497519, 7159191, 20545393, 59028011, 169782251, 488892391, 1409342969, 4067217153, 11750311255, 33983345183, 98387605609, 285144063989, 827236307471, 2402300281607, 6983098390213, 20318073613437, 59172567046657 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..1000

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: A101197 A233828 A101168 * A211290 A211299 A211301

Adjacent sequences:  A211284 A211285 A211286 * A211288 A211289 A211290

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 September 27 10:35 EDT 2020. Contains 337380 sequences. (Running on oeis4.)