OFFSET
0,3
COMMENTS
Computed using Burnside's orbit-counting lemma.
LINKS
María Merino, Rows n=0..35 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) = (7^(m*n) + 3*7^(m*n/2))/4;
for even n and odd m: T(n,m) = (7^(m*n) + 7^((m*n+n)/2) + 2*7^(m*n/2))/4;
for odd n and even m: T(n,m) = (7^(m*n) + 7^((m*n+m)/2) + 2*7^(m*n/2))/4;
for odd n and m: T(n,m) = (7^(m*n) + 7^((m*n+n)/2) + 7^((m*n+m)/2) + 7^((m*n+1)/2))/4.
EXAMPLE
Triangle begins:
============================================================================
n\m | 0 1 2 3 4 5
----|-----------------------------------------------------------------------
0 | 1
1 | 1 7
2 | 1 28 637
3 | 1 196 30184 10151428
4 | 1 1225 1443001 3461821825 8308236966001
5 | 1 8575 70656628 1186972525900 19948070175962425 335267157313994232775
...
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
María Merino, Imanol Unanue, Yosu Yurramendi, May 15 2017
STATUS
approved