OFFSET
0,2
LINKS
Jim Conant, Illustration for a(2) = 3.
Jim Conant, Illustration for a(4) = 12.
Jim Conant, Illustration for a(5) = 30.
N. J. A. Sloane, Illustration for a(6) = 90. (The largest empty region has size 10 X 9.)
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Scott R. Shannon and N. J. A. Sloane, Sep 14 2020
STATUS
approved