A266735 Number of words on {1,1,2,2,3,3,...,n,n} avoiding the pattern 12345.

1, 1, 6, 90, 2520, 102011, 5176504, 307027744, 20472135280, 1496594831506, 117857270562568, 9869468603141427, 870255083860881152, 80185525536941657225, 7673807618627318341436, 759049283017632212000140, 77292554293281131959377376, 8075621155990277422800518076

Offset: 0

Author

N. J. A. Sloane, Jan 06 2016

Keywords

• nonn

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, 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

Crossrefs

Cf. A000680, A220097, A266734.

Column k=4 of A267479.

Extensions

More terms from Alois P. Heinz, Jan 14 2016