OFFSET
0,3
COMMENTS
Computed using Burnsides orbit-counting lemma.
LINKS
María Merino, Rows n=0..33 of triangle, flattened
M. Merino and I. Unanue, Counting squared grid patterns with Pólya Theory, EKAIA, 34 (2018), 289-316 (in Basque).
FORMULA
For even n and m: T(n,m) = (9^(m*n) + 3*9^(m*n/2))/4;
for even n and odd m: T(n,m) = (9^(m*n) + 9^((m*n+n)/2) + 2*9^(m*n/2))/4;
for odd n and even m: T(n,m) = (9^(m*n) + 9^((m*n+m)/2) + 2*9^(m*n/2))/4;
for odd n and m: T(n,m) = (9^(m*n) + 9^((m*n+n)/2) + 9^((m*n+m)/2) + 9^((m*n+1)/2))/4.
EXAMPLE
Triangle begins:
==========================================================
n\m | 0 1 2 3 4
----|-----------------------------------------------------
0 | 1
1 | 1 9
2 | 1 45 1701
3 | 1 405 134865 97135605
4 | 1 3321 10766601 70618411521 463255079498001
...
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
María Merino, Imanol Unanue, Yosu Yurramendi, May 16 2017
STATUS
approved