OFFSET
0,2
COMMENTS
Computed using Burnside's orbit-counting lemma.
LINKS
María Merino, Table of n, a(n) for n = 0..35
M. Merino and I. Unanue, Counting squared grid patterns with Pólya Theory, EKAIA, 34 (2018), 289-316 (in Basque).
FORMULA
a(n) = (1/8)*(6^(n^2) + 2*6^(n^2/4) + 3*6^(n^2/2) + 2*6^((n^2 + n)/2)) if n is even;
a(n) = (1/8)*(6^(n^2) + 2*6^((n^2 + 3)/4) + 6^((n^2 + 1)/2) + 4*6^((n^2 + n)/2)) if n is odd.
MATHEMATICA
Table[1/8*(6^(n^2) + 2*6^((n^2 + 3 #)/4) + (3 - 2 #)*6^((n^2 + #)/2) + (2 + 2 #)*6^((n^2 + n)/2)) &@ Boole[OddQ@ n], {n, 10}] (* Michael De Vlieger, May 08 2017 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
María Merino, Imanol Unanue, Yosu Yurramendi, May 08 2017
STATUS
approved