OFFSET
1,2
LINKS
StackExchange, two-colorings of triangular arrays
MAPLE
Q:= proc(n)
if n mod 3 = 1 then 1/3*2^(1/2*n*(n + 1)) + 1/3*2^(2 + 1/6*(n - 1)*(n + 2))
else 1/3*2^(1/2*n*(n + 1)) + 1/3*2^(1 + 1/6*n*(n + 1))
end if
end proc
CROSSREFS
KEYWORD
nonn
AUTHOR
Marko Riedel, Apr 28 2014
STATUS
approved