49401

Appears in sequences

• Number of perfect matchings (or domino tilings) in W_5 X P_2n.at n=2A003735
• Numerator of Euler(n, 9/20).at n=4A156757
• 1/2 the number of n X n arrays of squares of integers with every 2X2 subblock summing to 20.at n=12A159221
• a(n)=(n^4-n^3-n^2-n)/2.at n=18A171129
• Number of chess diagrams that can be obtained in exactly one way in n plies and cannot be obtained in fewer plies. This is also the number of dual-free shortest proof games in n plies.at n=5A209080
• Number of decimal strings of length n that contain a specific string xy where x and y are distinct digits.at n=5A322052
• Array read by antidiagonals: T(m,n) = number of placements of zero or more dominoes on the m X n grid where no two empty squares are horizontally adjacent.at n=47A332862
• a(n) = 5*n^4 - 6*n^2 + 1. Column 4 of A378066.at n=10A378064