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

Author

Dan Hoey

Keywords

• nonn

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.

Crossrefs

Cf. A001168, A048663.

A row of A094166.

Programs

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 *)

Formula

a(n) = n * A001168(n). - Andrew Howroyd, Dec 04 2018

Extensions

More terms from Richard C. Schroeppel, May 04 2004