A006765 Number of strictly 2-dimensional polyominoes with n cells.

0, 0, 1, 4, 11, 34, 107, 368, 1284, 4654, 17072, 63599, 238590, 901970, 3426575, 13079254, 50107908, 192622051, 742624231, 2870671949, 11123060677, 43191857687, 168047007727, 654999700402, 2557227044763, 9999088822074, 39153010938486, 153511100594602, 602621953061977, 2368347037571251, 9317706529987949, 36695016991712878

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn

Comments

A000105 is the main entry for this sequence.

References

• Dan Hoey, Bill Gosper and Richard C. Schroeppel, Discussions in Math-Fun Mailing list, circa Jul 13 1999.
• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

• John Mason, Table of n, a(n) for n = 1..50 (terms 1..45 from N. J. A. Sloane)
• W. F. Lunnon, Counting multidimensional polyominoes. Computer Journal 18 (1975), no. 4, pp. 366-367.
• R. C. Schroeppel, A few mathematical experiments, Experimental Mathematics Workshop, Oakland, California, March 30, 2004.

Crossrefs

Equals A000105(n)-1. A row of A049429. A column of A049430.

Programs

Mathematica

Cases[Import["https://oeis.org/A000105/b000105.txt", "Table"], {, }][[All, 2]] - 1 // Rest (* Jean-François Alcover, Jan 21 2020 *)

Extensions

Edited by N. J. A. Sloane, Sep 23 2011

Name clarified by John Mason, Jan 10 2023