login
A354850
a(n) is the number of free polyominoes of width 4 and size n.
2
1, 3, 21, 59, 198, 703, 2568, 8421, 26165, 78074, 229881, 668082, 1928220, 5523946, 15745682, 44666804, 126251748, 355692380, 999498933, 2802212026, 7841587533, 21907928927, 61123152811, 170333279738, 474197771123, 1319004492132, 3666181193067, 10183729521212
OFFSET
4,2
COMMENTS
The sequence can be generated using a series of recursive formulas in a fashion similar to A352720 and A353067. These require respectively around 500 and 62000 formula lines, whereas a(n) requires about 10 million lines.
CROSSREFS
KEYWORD
nonn
AUTHOR
John Mason, Jun 08 2022
STATUS
approved