A165766 Number of tatami-free rooms of size 2n.

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 2, 0, 0, 1, 0, 1, 0

Offset: 1

Author

M. F. Hasler, Sep 26 2009

Keywords

• nonn

Comments

Number of pairs (r,c) such that r<=c, r*c=2n and A068920(r,c)=0.

A165632 lists twice the indices of nonzero terms, i.e. A165632 = { 2n | a(n)=0 }.