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

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!)
 A211286 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, 1, 3]. 0
 1, 3, 9, 25, 70, 195, 545, 1526, 4284, 12056, 34013, 96195, 272718, 775011, 2207557, 6302309, 18031941, 51702239, 148548283, 427644891, 1233449265, 3564068374, 10316244428, 29909714061, 86852526228, 252579033621, 735567723900, 2144990584607, 6262870100183, 18307786519038, 53577582619466 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS 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: A244934 A291594 A007046 * A211285 A333498 A097861 Adjacent sequences:  A211283 A211284 A211285 * A211287 A211288 A211289 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.

Last modified December 7 06:09 EST 2021. Contains 349567 sequences. (Running on oeis4.)