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A048664
Number of rooted 2-dimensional polyominoes with n square cells, with no symmetries removed.
2
1, 4, 18, 76, 315, 1296, 5320, 21800, 89190, 364460, 1487948, 6070332, 24750570, 100868236, 410919990, 1673486992, 6813529348, 27734769756, 112874034844, 459295593200, 1868653768443, 7601716598916, 30920563717052, 125759730486432, 511445050400275, 2079809585544808, 8457048866652588, 34386482811155244
OFFSET
1,2
REFERENCES
Dan Hoey, Bill Gosper and Richard C. Schroeppel, Discussions in Math-Fun Mailing list, circa Jul 13 1999.
LINKS
Jean-François Alcover, Table of n, a(n) for n = 1..56
R. C. Schroeppel, A few mathematical experiments, Experimental Mathematics Workshop, Oakland, 2004.
FORMULA
a(n) = n * A001168(n). - Andrew Howroyd, Dec 04 2018
MATHEMATICA
A001168 = Cases[Import["https://oeis.org/A001168/b001168.txt", "Table"], {_, _}][[All, 2]];
a[n_] := n A001168[[n]];
Array[a, 56] (* Jean-François Alcover, Sep 08 2019, after Andrew Howroyd *)
CROSSREFS
A row of A094166.
Sequence in context: A066259 A172159 A084213 * A108012 A291417 A017958
KEYWORD
nonn
AUTHOR
EXTENSIONS
More terms from Richard C. Schroeppel, May 04 2004
STATUS
approved