|
|
A370199
|
|
a(n) is the number of odd polyominoes with n cells.
|
|
0
|
|
|
0, 1, 3, 11, 35, 108, 380, 1348, 5014, 18223, 67634, 252849, 950346, 3602437, 13697333, 52293534, 200399576, 770410271, 2970369338, 11482572252, 44492417777, 172766286339, 672186167762, 2619985274260, 10228841840226, 39996338183554, 156612016049122
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,3
|
|
COMMENTS
|
Whether a polyomino is "odd" is determined by the fact that the permutation defined by assigning the positions from row- or column-wise enumeration of its cells on a square grid is an odd permutation. See the description in the 'Ponder This' challenge for the exact definition.
The terms a(1)-a(10) were given in this description, and a(11)-a(20) were in the solution. The larger terms are results of the program that the user "uau" provided in the Mersenne forum.
|
|
LINKS
|
User uau, C program, post in mersenneforum, Jul 22, 2022.
|
|
FORMULA
|
|
|
PROG
|
(C) See the 'user uau' link.
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,hard,more
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|