OFFSET
0,3
COMMENTS
Computed using Burnside's orbit-counting lemma.
LINKS
María Merino, Rows n=0..36 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) = (6^(m*n) + 3*6^(m*n/2))/4;
for even n and odd m: T(n,m) = (6^(m*n) + 6^((m*n+n)/2) + 2*6^(m*n/2))/4;
for odd n and even m: T(n,m) = (6^(m*n) + 6^((m*n+m)/2) + 2*6^(m*n/2))/4;
for odd n and m: T(n,m) = (6^(m*n) + 6^((m*n+n)/2) + 6^((m*n+m)/2) + 6^((m*n+1)/2))/4.
EXAMPLE
Triangle begins:
============================================================================
n\m | 0 1 2 3 4 5
----|-----------------------------------------------------------------------
0 | 1
1 | 1 6
2 | 1 21 351
3 | 1 126 12096 2544696
4 | 1 666 420876 544638816 705278736576
5 | 1 3996 15132096 117564302016 914040184444416 7107572245840091136
...
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
María Merino, Imanol Unanue, Yosu Yurramendi, May 15 2017
STATUS
approved