OFFSET
0,2
COMMENTS
Turning over is allowed.
See A132100 for definition and comments.
MAPLE
# B(n, m) gives the number of n-sided tiles with m points per side, allowing reflections (cf. comments in A132100)
with(numtheory): a:=(p, r)->piecewise(p mod 2 = 1, p^(r/2)*doublefactorial(r-1), sum(p^j*binomial(r, 2*j)*doublefactorial(2*j - 1), j = 0 .. floor(r/2)));
B := (n, m)->piecewise(n*m mod 2=1, 0, add(phi(p)*a(p, m*n/p), p in divisors(n))/(2*n) + piecewise(m mod 2=0, a(2, m*n/2)*2, a(2, m*n/2)+a(2, m*n/2-1))/4);
CROSSREFS
KEYWORD
nonn
AUTHOR
Keith F. Lynch, Oct 31 2007
EXTENSIONS
More terms from Laurent Tournier, Jul 09 2014
STATUS
approved