OFFSET
1,3
REFERENCES
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
A. J. Guttmann and I. G. Enting, The size and number of rings on the square lattice, J. Phys. A 21 (1988), L165-L172.
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
Name corrected, more terms from Andrey Zabolotskiy, Nov 09 2018
STATUS
approved