OFFSET
1,2
COMMENTS
Is this an erroneous version of A056780? It is unclear why one of the 9 polyominoes counted in A056780(4) should be omitted here. Devisme writes in his article that errors are likely and he cannot guarantee the exact figures but only "the order of magnitude". - M. F. Hasler, Feb 24 2018
REFERENCES
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
J. Devisme, Contribution à l'étude du problème des timbres-poste, Sphinx, 7 (Dec. 1937), 202-203. [Annotated scanned copy. Keep this link because it shows the marginal notes.]
J. Devisme, Enhanced scan of first page
J. Devisme, Enhanced scan of second page
N. J. A. Sloane, Illustration of initial terms
CROSSREFS
KEYWORD
nonn,nice,more
AUTHOR
STATUS
approved