OFFSET
0,3
LINKS
Ferenc Balogh, A generalization of Gessel's generating function to enumerate words with double or triple occurrences in each letter and without increasing subsequences of a given length, preprint arXiv:1505.01389 [math.CO], 2015.
Shalosh B. Ekhad and Doron Zeilberger, The Generating Functions Enumerating 12..d-Avoiding Words with r occurrences of each of 1,2, ..., n are D-finite for all d and all r, 2014
Nathaniel Shar, Experimental methods in permutation patterns and bijective proof, PhD Dissertation, Mathematics Department, Rutgers University, May 2016.
FORMULA
Conjecture: a(n) = (2/Pi)*Integral_{t=0..1} sqrt((1 - t)/t)*(64*t^3 - 32*t^2)^n = Catalan(3*n)*2F1(-1-3*n,-n;1/2-3*n;1/2). - Benedict W. J. Irwin, Oct 05 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jan 06 2016
EXTENSIONS
More terms from Alois P. Heinz, Jan 14 2016
STATUS
approved