OFFSET
1,2
LINKS
Rintaro Matsuo, Table of n, a(n) for n = 1..32
Vaclav Kotesovec, Non-attacking chess pieces, 6ed, 2013, p. 73, 405.
Eric Weisstein's World of Mathematics, Independent Vertex Set
Eric Weisstein's World of Mathematics, Torus Grid Graph
MATHEMATICA
a[n_] := With[{sets = Select[Tuples[{0, 1}, n], Count[#*RotateLeft[#], 1] == 0 &]}, Tr[MatrixPower[Table[Boole[Count[s1*s2, 1] == 0], {s1, sets}, {s2, sets}], n]]];
Table[a[n], {n, 1, 10}] (* Pjotr Buys, Jun 07 2023 *)
CROSSREFS
KEYWORD
nonn,nice,hard
AUTHOR
EXTENSIONS
Terms a(14)-a(16) from Vaclav Kotesovec, Dec 02 2011
STATUS
approved