184023

Appears in sequences

• Number of permutations of length n which avoid the patterns 1234, 1243, 3421.at n=17A116762
• Number of even-length first columns in all deco polyominoes of height n. A deco polyomino is a directed column-convex polyomino in which the height, measured along the diagonal, is attained only in the last column.at n=8A121696