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A177573
Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, up, down, up, up
0
1, 6, 89, 2436, 106394, 6773372, 592215536, 68125576354, 9976045410328, 1812109480941532
OFFSET
1,2
CROSSREFS
Sequence in context: A355187 A100297 A177568 * A166782 A121249 A113404
KEYWORD
nonn
AUTHOR
R. H. Hardin May 10 2010
STATUS
approved