A006758 Number of strictly 2-dimensional one-sided polyominoes with n cells.

0, 0, 0, 1, 6, 17, 59, 195, 703, 2499, 9188, 33895, 126758, 476269, 1802311, 6849776, 26152417, 100203193, 385221142, 1485200847, 5741256763, 22245940544, 86383382826, 336093325057, 1309998125639, 5114451441105, 19998172734785, 78306011677181, 307022182222505, 1205243866707467, 4736694001644861, 18635412907198669

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn

Comments

A000988 is the main entry for this sequence.

This version counts only polyominoes that are strictly 2-dimensional - it excludes those where all the squares are in a single line. Thus a(n) = A000988(n) - 1. - John Mason, Feb 18 2021

The value of a(11) in Table 1 (p. 366) of Lunnon (1975) is incorrect, and was corrected here by N. J. A. Sloane in 2011. - Petros Hadjicostas, Jan 11 2019

References

• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

• N. J. A. Sloane, Table of n, a(n) for n = 0..45 [a(0)=0 inserted by _Georg Fischer_, Jun 25 2020]
• W. F. Lunnon, Counting multidimensional polyominoes, Computer Journal 18 (4) (1975) 366-367.

Crossrefs

A000988 (= a(n) + 1) is another version. A column of A195738.

Extensions

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

a(0)=0 inserted by Sean A. Irvine, Jun 24 2020

Name clarified by John Mason, Feb 18 2021