cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-2 of 2 results.

A071332 Number of polyiamonds with n cells that tile the plane.

Original entry on oeis.org

1, 1, 1, 3, 4, 12, 23, 66, 139, 341, 567, 2034, 2495, 6354, 12908, 30261, 26556, 110145, 95967, 377523, 499672, 788726, 845130, 4998370, 3694670, 7406217, 13175181, 33557076, 22381719, 117770863
Offset: 1

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Author

Joseph Myers, May 19 2002

Keywords

References

  • M. Gardner, Tiling with Polyominoes, Polyiamonds and Polyhexes. Chap. 14 in Time Travel and Other Mathematical Bewilderments. New York: W. H. Freeman, pp. 175-187, 1988.

Crossrefs

Equals A000577-A071333 and equals A070765-A071334, cf. A054359, A070766.

Extensions

More terms from Joseph Myers, Nov 11 2003
a(29) and a(30) from Joseph Myers, Nov 21 2010

A071334 Number of polyiamonds with n cells without holes that do not tile the plane.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 1, 0, 20, 103, 594, 1192, 6290, 18099, 54808, 159048, 502366, 1374593, 4076218, 11378831, 32674779, 93006494, 264720498, 748062099, 2134512296, 6071524897, 17289205132, 49268564671, 140605019208, 401392287316
Offset: 1

Views

Author

Joseph Myers, May 19 2002

Keywords

Comments

From Bernard Schott, Feb 21 2020: (Start)
There exist 112 polyiamonds without holes that have from 1 to 8 cells (A070765), but only one of these polyiamonds, corresponding to a(7)= 1 cannot tile the plane. This polyiamond is called V-shaped heptiamond (see proof in Martin Gardner's link in German).
\ /\ /\ /
\/\/\/
\ /\ /
\/\/
(End)

References

  • M. Gardner, Tiling with Polyominoes, Polyiamonds and Polyhexes. Chap. 14 in Time Travel and Other Mathematical Bewilderments. New York: W. H. Freeman, pp. 175-187, 1988.

Crossrefs

Programs

  • Mathematica
    A[s_Integer] := With[{s6 = StringPadLeft[ToString[s], 6, "0"]}, Cases[ Import["https://oeis.org/A" <> s6 <> "/b" <> s6 <> ".txt", "Table"], {, }][[All, 2]]];
    A000577 = A@000577;
    A070764 = A@070764;
    A071332 = A@071332;
    a[n_] := A000577[[n]] - A070764[[n]] - A071332[[n]];
    a /@ Range[30] (* Jean-François Alcover, Feb 21 2020 *)

Extensions

More terms from Joseph Myers, Nov 11 2003
a(29) and a(30) from Joseph Myers, Nov 21 2010
Showing 1-2 of 2 results.