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 1-4 of 4 results.

A000104 Number of n-celled free polyominoes without holes.

Original entry on oeis.org

1, 1, 1, 2, 5, 12, 35, 107, 363, 1248, 4460, 16094, 58937, 217117, 805475, 3001127, 11230003, 42161529, 158781106, 599563893, 2269506062, 8609442688, 32725637373, 124621833354, 475368834568, 1816103345752, 6948228104703, 26618671505989, 102102788362303
Offset: 0

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Author

Keywords

References

  • J. S. Madachy, Pentominoes - Some Solved and Unsolved Problems, J. Rec. Math., 2 (1969), 181-188.
  • George E. Martin, Polyominoes - A Guide to Puzzles and Problems in Tiling, The Mathematical Association of America, 1996
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Cf. A000105, row sums of A308300, A006746, A056877, A006748, A056878, A006747, A006749, A054361, A070765 (polyiamonds), A018190 (polyhexes), A266549 (by perimeter).

Formula

a(n) = A000105(n) - A001419(n). - John Mason, Sep 06 2022
a(n) = (4*A056879(n) + 4*A056881(n) + 4*A056883(n) + 6*A056880(n) + 6*A056882(n) + 6*A357647(n) + 7*A357648(n) + A006724(n)) / 8. - John Mason, Oct 10 2022

Extensions

Extended to n=26 by Tomás Oliveira e Silva
a(27)-a(28) from Tomás Oliveira e Silva's page added by Andrey Zabolotskiy, Oct 02 2022

A054360 Number of polyominoes with n cells that do not tile the plane.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 4, 26, 235, 1585, 10453, 40151, 199922, 792867, 3146993, 12532362, 49280874, 189564720, 739243108, 2858545267, 11101139486, 43154849550, 167993679964, 654778791594, 2556955750961
Offset: 1

Views

Author

Joe Keane (jgk(AT)jgk.org)

Keywords

Examples

			a(7) = 4.
		

References

  • Posting by Glenn C. Rhoads (rhoads(AT)paul.rutgers.edu) to rec.puzzles, Feb 17 2000.

Crossrefs

Extensions

Corrected and extended by Joseph Myers, May 05 2002
More terms from Joseph Myers, Nov 04 2003
a(24) and a(25) from Joseph Myers, Nov 17 2010

A070768 Number of polyhexes with n cells without holes that do not tile the plane.

Original entry on oeis.org

0, 0, 0, 0, 0, 4, 37, 381, 2717, 18760, 116439, 565943, 3033697, 14835067, 72633658, 356923880, 1746833634, 8532601529, 41868336466, 205618704167, 1012359995953
Offset: 1

Views

Author

Joseph Myers, May 05 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

Extensions

More terms from Joseph Myers, Nov 06 2003
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), May 05 2007

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 1-4 of 4 results.