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 1-3 of 3 results.

A094167 Duplicate of A051738.

Original entry on oeis.org

1, 5, 30, 180, 1075, 6366, 37520, 220500, 1293615, 7581240, 44398387
Offset: 1

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Author

Keywords

A103465 Number of polyominoes that can be formed from n regular unit pentagons (or polypents of order n).

Original entry on oeis.org

1, 1, 2, 7, 25, 118, 551, 2812, 14445, 76092, 403976, 2167116, 11698961, 63544050, 346821209, 1901232614
Offset: 1

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Author

Sascha Kurz, Feb 07 2005; definition revised and sequence extended Apr 12 2006 and again Jun 09 2006

Keywords

Comments

Number of 5-polyominoes with n pentagons. A k-polyomino is a non-overlapping union of n regular unit k-gons.
Unlike A051738, these are not anchored polypents but simple polypents. - George Sicherman, Mar 06 2006
Polypents (or 5-polyominoes in Koch and Kurz's terminology) can have holes and this enumeration includes polypents with holes. - George Sicherman, Dec 06 2007

Examples

			a(3)=2 because there are 2 geometrically distinct ways to join 3 regular pentagons edge to edge.

Links

Crossrefs

Cf. A103465, A103466, A103467, A103468, A103469, A103470, A103471, A103472, A103473, A120102, A120103, A120104.
Cf. A000105, A000577, A000228.

Extensions

Entry revised by N. J. A. Sloane, Jun 18 2006

A094166 Array read by antidiagonals: T(n,k) = number of rooted 2-dimensional polyominoes with k cells, the cells being regular n-gons, with no symmetries removed.

Original entry on oeis.org

1, 1, 3, 1, 4, 9, 1, 5, 18, 28, 1, 6, 30, 76, 90, 1, 7, 33, 180, 315, 282, 1, 8, 42, 176, 1075, 1296, 875, 1, 9, 60, 252, 930, 6366, 5320, 2700, 1, 10, 81, 440, 1505, 4884, 37520, 21800, 8271, 1, 11, 105, 732, 3230, 8946, 25564, 220500, 89190, 25265
Offset: 1

Views

Author

N. J. A. Sloane, May 06 2004

Keywords

Examples

			Array begins:
1 3 9 28 90 282 875 2700 8271 25265 ...
1 4 18 76 315 1296 5320 21800 89190 364460 ...
1 5 30 180 1075 6366 37520 220500 1293615 7581240 ...
1 6 33 176 930 4884 25564 133512 696231 3626710 ...
1 7 42 252 1505 8946 53165 315980 1878597 11171930 ...
1 8 60 440 3230 23688 173796 1275240 9359748 68708320 ...
1 9 81 732 6660 60534 549801 4991436 45301356 411062595 ...
1 10 105 1080 11060 112932 1151430 11728960 119405565 1215105280 ...
1 11 132 1584 18920 225258 2677675 31805400 377611443 4481810410 ...
1 12 138 1564 17655 198936 2239860 25209144 283667850 3191677980 ...
1 13 156 1872 22425 268398 3212391 38454000 460400148 5513163565 ...
1 14 189 2520 33530 445788 5925976 78775480 1047251079 13923394730 ...

References

  • Dan Hoey, Bill Gosper and Richard C. Schroeppel, Discussions in Math-Fun Mailing list, circa Jul 13 1999.

Links

Crossrefs

Rows give A094164, A048664, A051738, A094165, A094168, A094169.

Extensions

More terms from Joshua Zucker, May 20 2006
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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