A048664 Number of rooted 2-dimensional polyominoes with n square cells, with no symmetries removed.

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

Cf. A001168, A048663.

A row of A094166.

Sequence in context: A066259 A172159 A084213 * A108012 A291417 A017958

Adjacent sequences: A048661 A048662 A048663 * A048665 A048666 A048667

Keyword

nonn

Author

Dan Hoey

Extensions

More terms from Richard C. Schroeppel, May 04 2004

Status

approved